Needs to be built with runtime/build-sharedlibs.sh and activated manually by
providing -defaultlib=llvmdc-runtime-shared -defaultlib=tango-cc-tango-shared
-defaultlib=tango-gc-basic-shared on llvmdc call at the moment.
To support D shared libraries in non-D code, we need to remove the main() from
libllvmdc-runtime-shared.