binutils/binutils: add option to enable gold

gold is a new, optimised, multi-threaded linker with support
for plugins.

Add support for gold starting with binutils 2.21. Although 2.20
also had gold, the configure flags have changed, and supporting
2.20 would be a mess in the code.

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

 reporter_name="Bart vdr. Meulen <bartvdrmeulen@gmail.com>"

 reporter_url=""

 reporter_comment="Config to build cross-compiler with mingw as kernel type"