fix broken sysconf when correct value is -1

this caused glib to try to allocate >2gb for getpwnam_r, and probably
numerous other problems.
fix overread (consuming an extra byte) scanning NAN

bug detected by glib test suite
skip leading zeros even after decimal point in floatscan

in principle this should just be an optimization, but it happens to
also fix a nasty bug where values like 0.00000000001 were getting
caught by the early zero detection path and wrongly scanned as zero.
make floatscan correctly set errno for overflow/underflow

care is taken that the setting of errno correctly reflects underflow
condition. scanning exact denormal values does not result in ERANGE,
nor does scanning values (such as the usual string definition of
FLT_MIN) which are actually less than the smallest normal number but
which round to a normal result.

only the decimal case is handled so far; hex float require a separate
fix to come later.
fix major breakage in iconv, bogus rejecting of dest charsets
add getresuid and getresgid syscall wrappers
add some ugly byte swapping cruft in endian.h
fix breakage in endian.h
remove redundant (unmaintained) check in floatscan

also be extra careful to avoid wrapping the circular buffer early
new gcc wrapper, entirely specfile based

the _concept_ of this wrapper has been tested extensively, but the
integration with the build/install system, and using a persistent
specfile rather than one generated at build-time, have not been
heavily tested and may need minor tweaks.

this approach should be a lot more robust (and easier to improve) than
writing a shell script that's responsible for trying to mimic gcc's
logic about whether it's compiling or linking, building shared libs or
executable files, etc. it's also lighter weight and should result in
mildly faster builds when using the wrapper.
getdtablesize is not standard; move it to its correct spot in unistd.h
implement getusershell, etc. legacy functions

I actually wrote these a month ago but forgot to integrate them. ugly,
probably-harmful-to-use functions, but some legacy apps want them...
make dlerror produce informative results

note that dlerror is specified to be non-thread-safe, so no locking is
performed on the error flag or message aside from the rwlock already
held by dlopen or dlsym. if 2 invocations of dlsym are generating
errors at the same time, they could clobber each other's results, but
the resulting string, albeit corrupt, will still be null-terminated.
any use of dlerror in such a situation could not be expected to give
meaningful results anyway.
destubify iswalpha and update iswpunct to unicode 6.1

alpha is defined as unicode property "Alphabetic" plus category Nd
minus ASCII digits minus 2 special-cased Thai punctuation marks
supposedly misclassified by Unicode as letters.

punct is defined as all of unicode except control, alphanumeric, and
space characters.

the tables were generated by a simple tool based on the code posted
previously to the mailing list. in the future, this and other code
used for maintaining locale/iconv/i18n data will be published either
in the main source repository or in a separate locale data generation
repository.
fix spurious punct class for some surrogate codepoints (invalid)

this happened due to their entries in UnicodeData.txt
optimize iswprint
sync case mappings with unicode 6.1

also special-case ß (U+00DF) as lowercase even though it does not have
a mapping to uppercase. unicode added an uppercase version of this
character but does not map it, presumably because the uppercase
version is not actually used except for some obscure purpose...
new wcwidth implementation (fast table-based)

i tried to go with improving the old binary-search-based algorithm,
but between growth in the number of ranges, bad performance, and lack
of confidence in the binary search code's stability under changes in
the table, i decided it was worth the extra 1.8k to have something
clean and maintainable.

also note that, like the alpha and punct tables, there's definitely
room to optimize the nonspacing/wide tables by overlapping subtables.
this is not a high priority, but i've begun looking into how to do it,
and i suspect the table sizes can be roughly halved. if that turns out
to be true, the new, fast, table-based implementation will be roughly
the same size as if i had just extended the old binary search one.
new internal locking primitive; drop spinlocks

we use priority inheritance futexes if possible so that the library
cannot hit internal priority inversion deadlocks in the presence of
realtime priority scheduling (full support to be added later).
internal locks: new owner of contended lock must set waiters flag

this bug probably would have gone unnoticed since it's only used in
the fallback code for systems where priority-inheritance locking
fails. unfortunately this approach results in one spurious wake
syscall on the final unlock, when there are no waiters remaining. the
alternative (possibly better) would be to use broadcast wakes instead
of reflagging the waiter unconditionally, and let each waiter reflag
itself; this saves one syscall at the expense of invoking the
"thundering herd" effect (worse performance degredation) when there
are many waiters.

ideally we would be able to update all of our locks to use an array of
two ints rather than a single int, and use a separate counter system
like proper mutexes use; then we could avoid all spurious wake calls
without resorting to broadcasts. however, it's not clear to me that
priority inheritance futexes support this usage. the kernel sets the
waiters flag for them (just like we're doing now) and i can't tell if
it's safe to bypass the kernel when unlocking just because we know
(from private data, the waiter count) that there are no waiters. this
is something that could be explored in the future.