[GlobalISel][X86] Refactor X86LegalizerInfo. NFC.
[GlobalISel][X86] Refactor X86LegalizerInfo. NFC.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@312234 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 4ebb481ded6217710ce2959b3a5f190065b8c8d1)

apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm