util,tests: Added compiler test script

util,tests: Added compiler test script

This script runs a series of compilations on gem5. The following
compilers are tested:

clang-9
clang-8
clang-7
clang-6
clang-5
clang-4
clang-3.9
gcc-9
gcc-8
gcc-7
gcc-6
gcc-5
gcc-4.8 (to be dropped soon:
         https://gem5.atlassian.net/browse/GEM5-218)

They are tested by building the following build targets:

ARM
ARM_MESI_Three_Level
Garnet_standalone
GCN3_X86
MIPS
NULL_MESI_Two_Level
NULL_MOESI_CMP_directory
NULL_MOESI_CMP_token
NULL_MOESI_hammer
POWER
RISCV
SPARC
X86
X86_MOESI_AMD_BASE

For each, ".opt" and ".fast" compiler build settings are tested.

clang-9 and gcc-9 are tested against all targets with each build
setting. For the remaining compilers, a random build target is
chosen. After the script has run, the output of the tests can be
found in "compile-test-out".

Docker is required to run this script.

Change-Id: Id3bf4c89b9d424c87e9409930ee2aceaef72cb29
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/30395
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>