Rewrite filesystem code (WIP)

This patch redoes the filesystem code from the FAT driver up to the
clipboard code in onplay.c.

Not every aspect of this is finished therefore it is still "WIP". I
don't wish to do too much at once (haha!). What is left to do is get
dircache back in the sim and find an implementation for the dircache
indicies in the tagcache and playlist code or do something else that
has the same benefit. Leaving these out for now does not make anything
unusable. All the basics are done.

Phone app code should probably get vetted (and app path handling
just plain rewritten as environment expansions); the SDL app and
Android run well.

Main things addressed:
1) Thread safety: There is none right now in the trunk code. Most of
what currently works is luck when multiple threads are involved or
multiple descriptors to the same file are open.

2) POSIX compliance: Many of the functions behave nothing like their
counterparts on a host system. This leads to inconsistent code or very
different behavior from native to hosted. One huge offender was
rename(). Going point by point would fill a book.

3) Actual running RAM usage: Many targets will use less RAM and less
stack space (some more RAM because I upped the number of cache buffers
for large memory). There's very little memory lying fallow in rarely-used
areas (see 'Key core changes' below). Also, all targets may open the same
number of directory streams whereas before those with less than 8MB RAM
were limited to 8, not 12 implying those targets will save slightly
less.

4) Performance: The test_disk plugin shows markedly improved performance,
particularly in the area of (uncached) directory scanning, due partly to
more optimal directory reading and to a better sector cache algorithm.
Uncached times tend to be better while there is a bit of a slowdown in
dircache due to it being a bit heavier of an implementation. It's not
noticeable by a human as far as I can say.

Key core changes:
1) Files and directories share core code and data structures.

2) The filesystem code knows which descriptors refer to same file.
This ensures that changes from one stream are appropriately reflected
in every open descriptor for that file (fileobj_mgr.c).

3) File and directory cache buffers are borrowed from the main sector
cache. This means that when they are not in use by a file, they are not
wasted, but used for the cache. Most of the time, only a few of them
are needed. It also means that adding more file and directory handles
is less expensive. All one must do in ensure a large enough cache to
borrow from.

4) Relative path components are supported and the namespace is unified.
It does not support full relative paths to an implied current directory;
what is does support is use of "." and "..". Adding the former would
not be very difficult. The namespace is unified in the sense that
volumes may be specified several times along with relative parts, e.g.:
"/<0>/foo/../../<1>/bar" :<=> "/<1>/bar".

5) Stack usage is down due to sharing of data, static allocation and
less duplication of strings on the stack. This requires more
serialization than I would like but since the number of threads is
limited to a low number, the tradoff in favor of the stack seems
reasonable.

6) Separates and heirarchicalizes (sic) the SIM and APP filesystem
code. SIM path and volume handling is just like the target. Some
aspects of the APP file code get more straightforward (e.g. no path
hashing is needed).

Dircache:
Deserves its own section. Dircache is new but pays homage to the old.
The old one was not compatible and so it, since it got redone, does
all the stuff it always should have done such as:

1) It may be update and used at any time during the build process.
No longer has one to wait for it to finish building to do basic file
management (create, remove, rename, etc.).

2) It does not need to be either fully scanned or completely disabled;
it can be incomplete (i.e. overfilled, missing paths), still be
of benefit and be correct.

3) Handles mounting and dismounting of individual volumes which means
a full rebuild is not needed just because you pop a new SD card in the
slot. Now, because it reuses its freed entry data, may rebuild only
that volume.

4) Much more fundamental to the file code. When it is built, it is
the keeper of the master file list whether enabled or not ("disabled"
is just a state of the cache). Its must always to ready to be started
and bind all streams opened prior to being enabled.

5) Maintains any short filenames in OEM format which means that it does
not need to be rebuilt when changing the default codepage.

Miscellaneous Compatibility:
1) Update any other code that would otherwise not work such as the
hotswap mounting code in various card drivers.

2) File management: Clipboard needed updating because of the behavioral
changes. Still needs a little more work on some finer points.

3) Remove now-obsolete functionality such as the mutex's "no preempt"
flag (which was only for the prior FAT driver).

4) struct dirinfo uses time_t rather than raw FAT directory entry
time fields. I plan to follow up on genericizing everything there
(i.e. no FAT attributes).

5) unicode.c needed some redoing so that the file code does not try
try to load codepages during a scan, which is actually a problem with
the current code. The default codepage, if any is required, is now
kept in RAM separarately (bufalloced) from codepages specified to
iso_decode() (which must not be bufalloced because the conversion
may be done by playback threads).

Brings with it some additional reusable core code:
1) Revised file functions: Reusable code that does things such as
safe path concatenation and parsing without buffer limitations or
data duplication. Variants that copy or alter the input path may be
based off these.

To do:
1) Put dircache functionality back in the sim. Treating it internally
as a different kind of file system seems the best approach at this
time.

2) Restore use of dircache indexes in the playlist and database or
something effectively the same. Since the cache doesn't have to be
complete in order to be used, not getting a hit on the cache doesn't
unambiguously say if the path exists or not.

Change-Id: Ia30f3082a136253e3a0eae0784e3091d138915c8
Reviewed-on: http://gerrit.rockbox.org/566
Reviewed-by: Michael Sevakis <jethead71@rockbox.org>
Tested: Michael Sevakis <jethead71@rockbox.org>
Add mempcpy implementation

A GNU extension that returns dst + size instead of dst. It's a nice
shortcut when copying strings with a known size or back-to-back blocks
and you have to do it often.

May of course be called directly or alternately through
__builtin_mempcpy in some compiler versions.

For ASM on native targets, it is implemented as an alternate entrypoint
to memcpy which adds minimal code and overhead.

Change-Id: I4cbb3483f6df3c1007247fe0a95fd7078737462b
Add normal alloca() definition and implement a strdupa and friends

Change-Id: I21c9c21fd664fb11bc8496ace4a389f535a030d6
Hopefully fix most of the errors and warnings from the last push

Change-Id: I1a466b2d55f120796910039a0296ca324c58e891
Get the last errors I hope!

Change-Id: Ia285b95480cc9ac6494b745d80892c4b1b912341
Fix last warning for Warble

Unused result warnings will have to be dealt with separately.

Change-Id: I00c45e28d4d43a5376745036e650ff8df576c2db
Remove I/O priority. It is harmful when used with the new file code.

HAVE_IO_PRIORITY was defined for native targets with dircache.

It is already effectively disabled for the most part since dircache no
longer lowers its thread's I/O priority. It existed primarily for the
aforementioned configuration.

Change-Id: Ia04935305397ba14df34647c8ea29c2acaea92aa
Superdom: some AI improvements and other minor changes

Change-Id: Ia2756a7263ec09b78714273af0f604fc9cdb50eb
Superdom: added option for persistent units

Change-Id: I4c28f3c567ed435ba7aee36c8b54c76fc75e12aa
Superdom: some AI improvements and other minor changes

Change-Id: Ia2756a7263ec09b78714273af0f604fc9cdb50eb
Merge branch 'superdomsplit'
Superdom: rewrote help text

Change-Id: I54d5ee920b03f24faee5a6bf53ca56b27bbdc6c8
[WIP] Superdom: AI can build factories/farms

Change-Id: I8e12765d8e70a0a1645b59a10cf5759b33d7740e
Added annoy-a-tron clone using piezo

Change-Id: I4ce6538bd349b5c408745e7539a902c5062a108e
Added annoy-a-tron to sources/category

Change-Id: I766b89e04ec68bdcc997cc788efe987a6bc2de21
Merge with upstream

Change-Id: I4e383eab9d20ad1f4f0524755abd5cce2d021d3d
Fix a small late creep-in goof in path parsing on native targets

Anything of one dot and one character (e.g. ".a") would get treated as
"." because I left out a condition when converting to recursionless
parsing of relative components. Git 'er fixed up.

Change-Id: Id5603ce0858b419dc08b1d496b4b187a573595f9
Merge branch 'vanilla'
Annoy-a-tron fixup

Change-Id: I185744be346cbe8fe919f8e7a9b7fd2a21a2fdf3
InfoNES - FS#2911 - NES Emulator for Color Targets  (WIP)

This is the source from a patch file available from the comments
section of FS#2911. Not much to comment about, fixed up some
files to make it compile against current git master as of (1/9/14).

* Compiles without warning or error
* Loads and runs .nes files
* The sound is awfully awful sounding

TODO:
* Keymaps
* Rotate screen setting
* Fix awful sound

Change-Id: Idb9a20fbee63a4e2ab001b3185f5a6118ed0afe9