testsuite: Fix up g++.dg/warn/Wuninitialized-32.C test for ilp32 [PR104373]

The testcase FAILs whenever size_t is not unsigned long:
FAIL: g++.dg/warn/Wuninitialized-32.C  -std=c++98 (test for excess errors)
Excess errors:
.../gcc/testsuite/g++.dg/warn/Wuninitialized-32.C:4:7: error: 'operator new' takes type 'size_t' ('unsigned int') as first parameter [-fpermissive]

Fixed by using __SIZE_TYPE__ instead of unsigned long.

2022-02-11  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/104373
	* g++.dg/warn/Wuninitialized-32.C (operator new[]): Use __SIZE_TYPE__
	as type of the first argument instead of unsigned long.