Fix broken tests for avr target

These tests assume {unsigned,} ints are 32 bits or wider. Explicitly
specify __{U}INT32_TYPE__ for targets with __SIZEOF_INT__ < 4.

gcc/testsuite/

2017-03-28  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>

	* gcc.c-torture/execute/pr79121.c:Use __{U}INT32_TYPE__ for targets
	with sizeof(int) < 4.
	* gcc.c-torture/execute/pr79737-1.c (struct S): Likewise.
	* gcc.c-torture/execute/pr79737-2.c: Likewise.
	* gcc.dg/torture/pr79777.c: Likewise.
	* gcc.dg/torture/pr79910.c: Likewise.

From-SVN: r246529