gnulib: Handle warnings introduced by updated gnulib

- Fix type of size variable in luks2_verify_key()
- Avoid redefinition of SIZE_MAX and ATTRIBUTE_ERROR
- Work around gnulib's int types on older compilers

Signed-off-by: Robbie Harwood <rharwood@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

config.h.in

@@ -149,4 +149,9 @@ typedef __UINT_FAST32_TYPE__ uint_fast32_t;
 #    define abort __builtin_trap
 #  endif /* !_GL_INLINE_HEADER_BEGIN */
 
+/* gnulib doesn't build cleanly with older compilers. */
+#  if __GNUC__ < 11
+_Pragma ("GCC diagnostic ignored \"-Wtype-limits\"")
+#  endif
+
 #endif