Add -B support to gcc-ar/ranlib/nm

Add -B support to gcc-ar/ranlib/nm

To use gcc-{ar,ranlib} for boot strap we need to add a -B option
to the tool. Since ar has weird and unusual argument conventions
implement the code by hand instead of using any libraries.

gcc/:

2014-09-01  Andi Kleen  <ak@linux.intel.com>

	* file-find.c (add_prefix_begin): Add.
	(do_add_prefix): Rename from add_prefix with first argument.
	(add_prefix): Add new wrapper.
	* file-find.h (add_prefix_begin): Add.
	* gcc-ar.c (main): Support -B option.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@214800 138bc75d-0d04-0410-961f-82ee72b054a4