Various x86 disassembler fixes.

Add VEX_LIG to scalar FMA4 instructions.
Use VEX_LIG in some of the inheriting checks in disassembler table generator.
Make use of VEX_L_W, VEX_L_W_XS, VEX_L_W_XD contexts.
Don't let VEX_L_W, VEX_L_W_XS, VEX_L_W_XD, VEX_L_W_OPSIZE inherit from their non-L forms unless VEX_LIG is set.
Let VEX_L_W, VEX_L_W_XS, VEX_L_W_XD, VEX_L_W_OPSIZE inherit from all of their non-L or non-W cases.
Increase ranking on VEX_L_W, VEX_L_W_XS, VEX_L_W_XD, VEX_L_W_OPSIZE so they get chosen over non-L/non-W forms.

llvm-svn: 191649