BUG: fix wheel platform tag for GraalPy

On the JVM sys.maxsize is 2**31-1 because Java arrays can be indexed
only with 32-bit indices also on 64bit platforms. Fix this by using
the same default implementation as found in stdlib platform module and
implemented in packaging.

mesonpy/_tags.py

@@ -6,6 +6,7 @@
 
 import os
 import platform
+import struct
 import sys
 import sysconfig
 import typing
@@ -25,7 +26,7 @@
 }
 
 
-_32_BIT_INTERPRETER = sys.maxsize <= 2**32
+_32_BIT_INTERPRETER = struct.calcsize('P') == 4
 
 
 def get_interpreter_tag() -> str: