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This makes sure that shared library built with MinGW toolchain is linked
statically to *all* its dependencies, including libc, libstdc++, libsdl2
and all the others. This allows producing of working `openrct2.dll` by
cross-compiling.

I hit a bug with libcrypto, a dependency of libssl, which in turn is a
dependency of curl, which creates a `DllMain` entrypoint for static lib
too, but since we don't do anything in ours, this should be safe.

I have only had chance to try it out when cross-compiling, ideally it
should be tested under Cygwin/MSYS too, but it is too bothersome to
setup for me.