Do not build the macOS installer with mimalloc enabled (#112312)

Do not build the macOS installer with mimalloc enabled pending resolution of
weak linking crashes during interpreter startup on macOS 10.9,
10.10, and 10.11 when built on macOS 11 and later.

Author: ned-deily

Mac/BuildScript/build-installer.py

@@ -1147,7 +1147,9 @@ def buildPython():
     # will find them during its extension import sanity checks.
 
     print("Running configure...")
+    print(" NOTE: --with-mimalloc=no pending resolution of weak linking issues")
     runCommand("%s -C --enable-framework --enable-universalsdk=/ "
+               "--with-mimalloc=no "
                "--with-universal-archs=%s "
                "%s "
                "%s "