Revert commit v3.9.0-rc1~148^2 (Do not assume GCC libs are linked by all
compilers, 2017-05-05).  Libraries such as `gcc_s` and `gcc_eh` are
*conditionally* implied by gcc based on how it is invoked.  They are not
safe to use arbitrarily, and so cannot be reported as part of gcc's
implicit libraries.  Another solution to mixing compiler vendors will be
needed.

Fixes: #17436