Improve check for int32_t being long or int

Improve check for int32_t being long or int

        * libc/include/sys/config.h: Move evaluation of _UINTPTR_EQ_ULONG and
        _UINTPTR_EQ_ULONGLONG from here...
        * libc/include/sys/_intsup.h: ...to here.  Rename to _INTPTR_EQ_LONG
        and _INTPTR_EQ_LONGLONG to refer to signed base type.  Add test for
        base type of int32_t and set _INT32_EQ_LONG accordingly.
        * libc/include/stdint.h: Change checks for __have_long32 to checks
        for _INT32_EQ_LONG.
        * libc/include/inttypes.h: Ditto.  Accommodate aforementioned name
        change.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>