Looking for a reviewer for two simple clang fixes

Hello!

I have two pending fixes for clang on Sparc on Linux. These are:

https://reviews.llvm.org/D90524
https://reviews.llvm.org/D90549

Basically, the first change adds a multilib workaround for 32-bit
Sparc on 64-bit Sparc that's already being used on X86 and PPC.

It fixes the various "FAIL: Builtins-sparc-linux" failures in the testsuite [1]:

Command Output (stderr):
--
/usr/bin/ld: cannot find crt1.o: No such file or directory
/usr/bin/ld: cannot find crti.o: No such file or directory
/usr/bin/ld: skipping incompatible /usr/lib/sparc64-linux-gnu/libc.so when searching for -lc
/usr/bin/ld: skipping incompatible /usr/lib/sparc64-linux-gnu/libc.a when searching for -lc
/usr/bin/ld: cannot find -lc
/usr/bin/ld: skipping incompatible /usr/lib/sparc64-linux-gnu/libc.so when searching for -lc
/usr/bin/ld: skipping incompatible /usr/lib/sparc64-linux-gnu/libm.so when searching for -lm
/usr/bin/ld: skipping incompatible /usr/lib/sparc64-linux-gnu/libm.a when searching for -lm
/usr/bin/ld: cannot find -lm
/usr/bin/ld: skipping incompatible /usr/lib/sparc64-linux-gnu/libm.so when searching for -lm
/usr/bin/ld: cannot find crtn.o: No such file or directory
clang-12: error: linker command failed with exit code 1 (use -v to see invocation)

The second change is necessary as the first fix causes the CHECK-DEBIAN-SPARC*
tests to fail. The second change switches these tests to modern Debian MultiArch
folders as it is already being used for other architectures on Debian such as PowerPC
and x86.

Could someone review those small changes for me and commit them? I have not been
able to find a reviewer yet.

Thanks,
Adrian