1. Fixing error where basic block labels were not being printed out when they...

1. Fixing error where basic block labels were not being printed out when they need to be for the MBlaze backend because AsmPrinter::isBlockOnlyReachableByFallthrough does not take into account delay slots.
2. Re-adding .mask and .frame directives in printed assembly.
3. Adding .ent and .end directives in printed assembly.
4. Minor cleanups to MBlaze backend.

llvm-svn: 120095