-arch option unavailable on Linux systems

[joshuacrotts]

The patch from using the -march flag to -arch in commit d732589 breaks compilation on Linux systems since -arch is only supported by Clang.

To fix, we can add a binding to compiler-tests-suite that removes the flag for non-MacOS ARM-based systems.

(let ([gcc-cmd (if (and (equal? (system-type 'os) 'macosx)
                        (equal? (system-type 'arch) 'aarch64))
                   "gcc -g -std=c99 -arch x86_64"
                   "gcc -g -std=c99")])
  (let ([gcc-output (system (format "~a runtime.o ./tests/~a.s -o ./tests/~a.out" gcc-cmd test-name test-name))])
    ...

[jsiek]

fixed, thanks!