This allows us to make TRC non-polymorphic and value-initializable, eliminating a huge static
initializer and a ton of cruft from the generated code.
Shrinks ARMBaseRegisterInfo.o by ~100k.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151806 91177308-0d34-0410-b5e6-96231b3b80d8