cmake: move asm-primitives.cpp and asm headers into VS source group

A cosmetic change only
primitives: cleanup intra prediction table dimensions
cmake: remove ENABLE_PRIMITIVES_VEC build option

The use of the few remaining compiler intrinsic functions is now unconditional.
Compiler detection will remove them cleanly in case they cannot be compiled, so
there is no reason to make them a top level build option
cmake: rename ENABLE_PRIMITIVES_ASM to ENABLE_ASSEMBLY

And use the same name for the build define.  Also, rename
Setup_Vector_Primitives() to Setup_Instrinsic_Primitives()
cmake: bump X265_BUILD post 0.6, since x265_param has changed