Allow user to override ASan default shadow scaleshadow scale in compiler_rt by passing
-DLLVM-DCOMPILER_RT_ASAN_SHADOW_SCALE=5n to CMake. Restrict legal values to shadowPropagate the override
sshadow scale we plan to test for: 3value via a compiler define to compiler-rt and 5.asan
Propagate the shadow scale value via a compiler define to llvm,tests. Tests will use the define to partially disable unsupported
Set "-mllvm -asan-mapping-scale -mllvm <n>" for compiler_rt tests
that are compiled with -fsanitize=address.
compiler-rt, and asan tests.