RFC: deprecate BR2_GCC_SHARED_LIBGCC

I've been playing around a bit with the options of the buildroot toolchain,
and disabled BR2_GCC_SHARED_LIBGCC. Turns out that this makes it impossible to build shared C++ libraries, because they have to be linked with a shared libstdc++.so... Also, it looks like libgcc_s.so is still built, but it isn't copied to the target directory. So there's a risk that something links against it and fails to run.

So I propose to remove the BR2_GCC_SHARED_LIBGCC option, and instead make it
equal to !BR2_PREFER_STATIC. That will probably still cause problems in some corner cases, but we reduce the room for error.

Regards,
Arnout

Arnout Vandecappelle                               arnout at mind be
Senior Embedded Software Architect                 +32-16-286540
Essensium/Mind                                     http://www.mind.be
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