[clang] Add options to build with host compiler

On platforms for which no clang binaries are shipped, it can be useful
to reuse the scripts to build clang natively. However in this case, we
cannot download the previous clang version.

This adds --host-cc and --host-cxx options to use a host compiler to
build clang.

Change-Id: I31f431bc52a668f2613a2c57e23727f002581c5b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3635499
Commit-Queue: Pierre Langlois <pierre.langlois@arm.com>
Reviewed-by: Arthur Eubanks <aeubanks@google.com>
Cr-Commit-Position: refs/heads/main@{#1005835}
NOKEYCHECK=True
GitOrigin-RevId: 7010f5ff5fb1ea292c7c7bb703ac5fee3d15846f
1 file changed