Fix Windows and possibly BSDs

Author: JukkaL

mypyc/common.py

@@ -45,7 +45,7 @@
 
 IS_32_BIT_PLATFORM: Final = int(SIZEOF_SIZE_T) == 4
 
-X86_64: Final = platform.machine() == "x86_64"
+X86_64: Final = platform.machine() in ("x86_64", "AMD64", "amd64")
 
 PLATFORM_SIZE = 4 if IS_32_BIT_PLATFORM else 8