tools/build/make.py: Don't call brew --prefix if --cross-bindir is set

Also updated the logic to use subprocess.run() instead of the old
subprocess.getoutput() which also includes stderr and therefore
can trigger an exception inside Path().exists().

Reported by: gnn

(cherry picked from commit a26ace4db6d974215a4d882948da80eae2b3b0d4)