Implement the skip_solib_resolver gdbarch hook for FreeBSD architectures.

Implement the skip_solib_resolver gdbarch hook for FreeBSD architectures.

The ELF runtime linker on all FreeBSD architectures uses the
"_rtld_bind" entry point for unresolved PTL entries.  FreeBSD/mips has
an additional entry point called "_mips_rtld_bind".

gdb/ChangeLog:

	* fbsd-tdep.c (fbsd_skip_solib_resolver): New function.
	(fbsd_init_abi): Install gdbarch "skip_solib_resolver" method.
	* fbsd-tdep.h (fbsd_skip_solib_resolver): New prototype.
	* mips-fbsd-tdep.c (mips_fbsd_skip_solib_resolver): New function.
	(mips_fbsd_init_abi): Install gdbarch "skip_solib_resolver"
	method.