util: Add some settings files for build_cross_gcc.

util: Add some settings files for build_cross_gcc.

These files have settings for 32 and 64 bit ARM, MIPS, POWER, RISCV, and
SPARC. When used with the versions of toolchain components below, they
all generate working hello world binaries.

binutils-2.34
gcc-9.3.0
glibc-2.31
linux-5.5.9
gdb-9.1

The script was unable to install the c++ standard headers (step 8)
because a constant was not found when building one of the sanitizers. I
don't know exactly why this happens, but I suspect it's independent of
the build process.

Change-Id: I9f0068b77edf338ed63b95f007454c07651aa42a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/26764
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: Gem5 Cloud Project GCB service account <345032938727@cloudbuild.gserviceaccount.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>