Enables -Db_sanitize=undefined and company.
Also serves as a testcase for NVCC comma-shielding: Because the test-
case declares `b_sanitize=address,undefined`, the host GCC compiler
needs `-fsanitize=address,undefined`, but this stands a danger of being
split by NVCC when wrapped with `-Xcompiler=args,args`. Special,
already-existing comma-shielding codepaths activate to prevent this
splitting.
Closes#8394
Eli Schwartz
Olexa Bilaniuk