Backed out changeset: 5df643257054

This was causing memory corruption when --tskip and --rd=2 were used together.
It needs to be further investigated and fixed on the default branch.

--HG--
branch : stable
vec: disable allangs 32x32 intrinsic primitive for clang

clang seems to compile it ok, and the testbench passes, but it causes runtime
exceptions when used within the encoder.

--HG--
branch : stable
y4m: initialize colorSpace to avoid crashes after failing to parse y4m header

--HG--
branch : stable
Merge with stable