[Bug testsuite/90812] Tests misuse "dg-require-effective-target int32plus" to check for 64-bit integer support

[jozefl.gcc at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90812

--- Comment #1 from Jozef Lawrynowicz <jozefl.gcc at gmail dot com> ---
To check for 64-bit integer support, it seems that the "stdint_types" effective
target keyword should be sufficient, although I'm not sure if it might be
possible for a target to provide __INT64_TYPE__ but not stdint.h.

Perhaps a new effective target keyword "int64type", which runs the following,
is required:
#ifndef __INT64_TYPE__
#error
#endif