Add support for DictZip enabled gzip files

DictZip is an extension to the gzip format that allows random seeks in gzip
compressed files by cutting the file into pieces and storing the piece offsets
in the "extra" header of the gzip format.

Thanks to that extension, we can use gzip compressed files as block backend,
though only in read mode.

This makes a lot of sense when stacked with tar files that can then be shipped
to VM users. If a VM image is inside a tar file that is inside a DictZip
enabled gzip file, the user can run the tar.gz file as is without having to
extract the image first.

Tar patch follows.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Bruce Rogers <brogers@novell.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Add tar container format

Tar is a very widely used format to store data in. Sometimes people even put
virtual machine images in there.

So it makes sense for qemu to be able to read from tar files. I implemented a
written from scratch reader that also knows about the GNU sparse format, which
is what pigz creates.

This version checks for filenames that end on well-known extensions. The logic
could be changed to search for filenames given on the command line, but that
would require changes to more parts of qemu.

The tar reader in conjunctiuon with dzip gives us the chance to download
tar'ed up virtual machine images (even via http) and instantly make use of
them.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Bruce Rogers <brogers@novell.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Legacy Patch kvm-qemu-preXX-dictzip3.patch
Legacy Patch kvm-qemu-preXX-report-default-mac-used.patch
console: add question-mark escape operator

Some termcaps (found using SLES11SP1) use [? sequences. According to man
console_codes (http://linux.die.net/man/4/console_codes) the question mark
is a nop and should simply be ignored.

This patch does exactly that, rendering screen output readable when
outputting guest serial consoles to the graphical console emulator.

Signed-off-by: Alexander Graf <agraf@suse.de>
Make char muxer more robust wrt small FIFOs

Virtio-Console can only process one character at a time. Using it on S390
gave me strage "lags" where I got the character I pressed before when
pressing one. So I typed in "abc" and only received "a", then pressed "d"
but the guest received "b" and so on.

While the stdio driver calls a poll function that just processes on its
queue in case virtio-console can't take multiple characters at once, the
muxer does not have such callbacks, so it can't empty its queue.

To work around that limitation, I introduced a new timer that only gets
active when the guest can not receive any more characters. In that case
it polls again after a while to check if the guest is now receiving input.

This patch fixes input when using -nographic on s390 for me.
linux-user: lseek: explicitly cast end offsets to signed

When doing lseek, SEEK_END indicates that the offset is a signed variable
that is usually negative, while and other SEEK indicates that it's unsigned.

When converting from 32bit to 64bit parameters, we need to take this into
account and enable SEEK_END to be negative, while other SEEKs usually indicate
absolute position which we need to maintain as unsigned.

Signed-off-by: Alexander Graf <agraf@suse.de>