jpeg-turbo: add simd support for powerpc cores with altivec
>From the 1.5-b1 release notes:
Added full SIMD acceleration for PowerPC platforms using AltiVec VMX
(128-bit SIMD) instructions. Although the performance of libjpeg-turbo on
PowerPC was already good, due to the increased number of registers available
to the compiler vs. x86, it was still possible to speed up compression by
about 3-4x and decompression by about 2-2.5x (relative to libjpeg v6b)
through the use of AltiVec instructions.
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>