[PATCH] MC: rename EmitWin64EH routines

[Reid Kleckner]

lgtm

Either SEH or WinCFI seem like reasonable names to me.  The information in question is analogous to DWARF's call frame information (CFI).  MinGW chose to call these directives .seh_foo, even though this stuff is more CFI-related than EH-related.  So, we could either standardize on the slightly weird directive names, or try to call it what it is.

http://reviews.llvm.org/D4125