Added support for -bf-static

For parity with the other Byfl wrapper scripts, added support for
static analysis of the code via the -bf-static command-line option.
Updated Makefile.llvm.rules for the latest llvm-ar

llvm-ar removed support for the "f" option in LLVM revision r186078
(2013-07-11).  This revision of Byfl correspondingly removes the "f"
from the llvm-ar command line specified in Makefile.llvm.rules.