This commit changed the initialization of best_mode_index to -1 to make
sure it is not mistakenly used for mode masking.

Change-Id: I75b05db51466070dd23c4ee57a4d4b40764dc019

Change-Id: I08aa0c213df34c084eb7a3c51b6b3306e49c7757

This reverts commit 22a3e307

Change-Id: I460d905edf5fb2006da58c18fbe02c04d0c631bb

Change-Id: I0462bf1ca1b4e5a1c06259979b4daff949b8a2c6

Change-Id: I1324c339815a47004ddccdaf651d24c60382b92f

Change-Id: Ie26b6ca8de733a527f820b16148e7a2231073f0f

Cleanup.

Change-Id: I54d989e24b35323cda7290654e425565d5c9ea2d

Change-Id: I721ff26e3d5dbef80b8cd2dd562adae3748f6687

Change-Id: I9be2e4e9aeda0fae6dc946deae2999be51daebe0

In mode selection loop, once mode_index pass mode_skip_start, all
modes with a different reference frame from current best mode are
masked out using mode_skip_mask.

However, the setting of mode_skip_mask may use an invalid mode if
there is no mode tested yet. This commit fixes the issue by making
sure a mode has been tested and selected. Otherwise, no mode will be
masked out because of their reference frame.

Change-Id: Ib0009e8a96836a65cf5347440fff8a2e1a67f29f

Change-Id: I9b8f9a3f4fa9d48695149dd68ecb5e8d84accafe

Change-Id: Idf612c772440158cd1645623241c51ab0d57405c

Change-Id: I7a5230852cb24ce22bfe85ea2608cdb4619b5200

Change-Id: I08fe184a04e5435aeac92f1d7cc9733ca52c2783

Change-Id: Ib64edeb58b3e25488fb85bbe85c9decb15b4d0a1

The macosx release of clang v5.0 identifies itself as:
Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)

This version of clang uses the older _mm_broadcastsi128_si256, like
v3.3, as given away in the LLVM svn version above.

Change-Id: I4d6d59d5454efd57d2ae9e75f5eb7486af7cbd0c

Change-Id: I3ced24f2c3b9cc483278c0f0d60512e7d2efa4f4