Makefile.vc: add a 'legacy' RTLIBCFG option

disables buffer security checks (/GS-) and any machine optimizations
(e.g., sse2)

fixes issue #228

Change-Id: I81fa483dc1654199b2017626320383d2d63317dc
dec_neon: add RD4 intra predictor

based on the SSE2 version; a bit rough around the loads, but still ~38%
faster.

Change-Id: I22426d939a7354cbc9a85ca8c68235d6081b882f
Merge "Makefile.vc: add a 'legacy' RTLIBCFG option"
Merge "dec_neon: add RD4 intra predictor"
Fix bug in VP8LCalculateEstimateForCacheSize.

The method VP8LCalculateEstimateForCacheSize is not evaluating the all possible
range for cache_bits.
Also added a small penality for choosing the larger cache-size. This is done to
strike a balance between additional memory/CPU cost (with larger cache-size) and
byte savings from smaller WebP lossless files.

This change saves about 0.07% bytes and speeds up compression by 8% (default
settings). There's small speedup at Q=50 along with byte savings as well.
Compression at Quality=25 is not effected by this change.

Change-Id: Id8f87dee6b5bccb2baa6dbdee479ee9cda8f4f77
Merge "Fix bug in VP8LCalculateEstimateForCacheSize."