On some distributions, e.g. openSUSE, the libraries for 64 bit
architectures end up stored in <target>/<triplet>/lib64 instead of
plain "lib".
(This is caused by their use of a site script for configure, which
overrides libdir when the host triplet matches 64 bit architecture
names - even if it's a triple for cross compilation for a totally
different OS. This only affects the libraries and not mingw-w64-crt,
as the crt's makefiles manually set the output directory name.)
This fixes https://github.com/mstorsjo/llvm-mingw/issues/51.
Martin Storsjö