Enable libcompiler_rt on Windows

This allows building libcompiler_rt for Windows, which is necessary to
build a native version of layoutlib.
This removes libunwindbacktrace and libunwind_static from the static
libraries, as they do not build on Windows and do not appear necessary
for libcompiler_rt.

Test: lunch sdk && make libcompiler_rt
Change-Id: I265fafb66d1e8213a10ab023df8e7256d5ab7831
1 file changed