cc/gcc: do not build plugins for static toolchains
Plugins are shared objects, and when building a toolchain statically,
the gcc build system breaks havok (although there is no hard technical
reasons it should not be possible)...
And consequently, do not enable plugin supoprt in binutils.
Reported-by: Thomas Spurden <thomas@ado.is-a-geek.net>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
(transplanted from 9139319423fd7d71017dfc974d3a06ab79e08fb8)