Fixed bf-inst code and documentation
Fixed bf-inst code and documentation

Due to changes in the Byfl build system and in LLVM/Clang's
processing, bf-inst stopped working.  Furthermore, the documentation
became inaccurate.  This revision attempts to make bf-inst work once
again and have documentation that correctly describes its usage.

losalamos/Byfl,losalamos/Byfl,losalamos/Byfl,losalamos/Byfl