Add more module targets for host, host-cross, host32, host64

Previously, clang-host would build the clang module for 32-bit and
64-bit for the host and for windows.  Make clang-host only compile
for host, and add clang-host-cross for windows.  Also add targets
that only build 32-bit or 64-bit: clang-host32, clang-host64,
clang-host-cross32, clang-host-cross64, clang-target32, and
clang-target64.

Test: inspect build.ninja
Change-Id: I7676f9497dfc852f2a0255dda8da06c88eec0db8