Revert r320461 - causing ICE in windows buildss

[X86] Use regular expressions more aggressively to reduce the number of scheduler entries needed for FMA3 instructions.

When the scheduler tables are generated by tablegen, the instructions are divided up into groups based on their default scheduling information and how they are referenced by groups for each processor. For any set of instructions that are matched by a specific InstRW line, that group of instructions is guaranteed to not be in a group with any other instructions. So in general, the more InstRW class definitions are created, the more groups we end up with in the generated files. Particularly if a lot of the InstRW lines only match to single instructions, which is true of a large number of the Intel scheduler models.

This change alone reduces the number of instructions groups from ~6000 to ~5500. And there's lots more we could do.

llvm-svn: 320470