[PATCH] Fix MipsLongBranch pass to work when the code has inline assembly.

[Mark Seaborn]

  > The code that extends MipsMCExpr class to handle %higher and %highest relocations is split into a separate patch.

  Thanks for splitting that out (in http://llvm-reviews.chandlerc.com/D3230).  It occurs to me now that you only need %higher/%highest if the jump offset is >4GB, which seems rather unlikely, if not downright impossible when compiling a single function.  You'd want to handle functions bigger than 64k but not functions bigger than 4GB. :-)

  Given that, would it make sense to drop the %higher/%highest instructions from the code sequence you generate on MIPS64, making the code a little smaller and faster?

http://llvm-reviews.chandlerc.com/D3089