Suppress warnings while testing a new compiler

The -Wmacro-redefined warning causes a build failure after building the
musl libc++ with the LIBCXX_HAS_MUSL_LIBC CMake var
(r.android.com/3355477).

Bug: http://b/379357589
Test: treehugger
Change-Id: I8b4f6f659609effef9fb283167c578f6b1d7ed9b