Transparent hugepage support

Combine frame and mb data mallocs into a single large malloc.
Additionally, on Linux systems with hugepage support, ask for hugepages on
large mallocs.

This gives a small performance improvement (~0.2-0.9%) on systems without
hugepage support, as well as a small memory footprint reduction.

On recent Linux kernels with hugepage support enabled (set to madvise or
always), it improves performance up to 4% at the cost of about 7-12% more
memory usage on typical settings..

It may help even more on Haswell and other recent CPUs with improved 2MB page
support in hardware.
Fix AVX2 detection bug with "limit CPUID" enabled in BIOS
AVC-Intra support

This format has been reverse engineered and x264's output has almost exactly
the same bitstream as Panasonic cameras and encoders produce. It therefore does
not comply with SMPTE RP2027 since Panasonic themselves do not comply with
their own specification. It has been tested in Avid, Premiere, Edius and
Quantel.

Parts of this patch were written by Jason Garrett-Glaser and some reverse
engineering was done by Joseph Artsimovich.
Fix cases in which intra refresh allowed prediction from disallowed pixels
configure: Support cygwin64