binutils: fix "Bad value" error in bfd for MIPS when using -Bsymbolic.

From OpenBSD's log:

Inspired by https://sourceware.org/ml/binutils/2010-08/msg00333.html,
but expressed differently so there are no GPLv3 issues.

Obtained from: OpenBSD (CVS rev. 1.7)
MFC after: 1 month