libstdc++: Fix configure test for 32-bit targets

The -mlarge model for msp430-elf uses 20-bit pointers, which means that
sizeof(void*) == 4 and so the r14-1432-g51cf0b3949b88b change gives the
wrong answer. Check __INTPTR_WIDTH__ >= 32 instead.

libstdc++-v3/ChangeLog:

	* acinclude.m4 (GLIBCXX_ZONEINFO_DIR): Fix for 32-bit pointers
	to check __INT_PTR_WIDTH__ instead of sizeof(void*).
	* configure: Regenerate.

(cherry picked from commit 2a919c08)