build: soong: windres: use clang to preprocess

Otherwise binaries under:
prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/bin/
are being invoked.

https://sourceware.org/binutils/docs-2.33.1/binutils/windres.html


states:
When windres reads an rc file, it runs it through the C preprocessor first.

Use the `--preprocessor` flag to specify the exact command to run. The
args to the preprocessor get wiped out when setting that flag, so
`-E -xc-header -DRC_INVOKED` must be re-passed, else clang will error as
it tries to invoke ld.

Once AOSP packages llvm-rc, aosp/1206346 can be rebased on top, so this
patch should be a short lived change.

Bug: 147295872
Test: <remove mingw gcc> && lunch aosp_x86-eng && \
  cd external/mdnsresponder && mm
Change-Id: Ic0e6b75e7e964ee9f9757e534cddd16438604c34
Suggested-by: Pirama Arumuga Nainar <pirama@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>