llvm-mc/AsmParser: Separate instruction ordering for ambiguity detection.

llvm-mc/AsmParser: Separate instruction ordering for ambiguity detection.
 - We want the ordering operation to be simple, since we run it on every
   match. The old ordering is also not a strict weak ordering when there are
   ambiguities, which makes MSVC unhappy.

 - While we are at it, detect all ambiguities instead of just the adjacent
   ones. There are actually 655, for X86.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78526 91177308-0d34-0410-b5e6-96231b3b80d8