new VariantKind to the MCSymbolExpr seems like overkill, but I'm not sure
there's a more straightforward way to get the printing difference captured.
(i.e., x86 uses @PLT, ARM uses (PLT)).
llvm-svn: 114613
functions in ARMBaseInfo.h so it can be used in the MC library as well.
For anything bigger than this, we may want a means to have a small support
library for shared helper functions like this. Cross that bridge when we
come to it.
llvm-svn: 114016