binutils/binutils: add blind option to force use of ld.bfd during build

gold is not capable of building glibc/eglibc, so we have to
force using the BFD linker, ld.bfd.

Offer a blind option that affected components can select to
force use of the BFD linker during the build.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# Default test suite configuration

# Default DejaGnu configuration

DG_TOOLNAME = gcc

DG_TARGET_HOSTNAME = 127.0.0.1

DG_TARGET_USERNAME = root

# Default tests

DG_C_TESTS = 

DG_CPP_TESTS =