Fix bogus pr31096-1.c failure for avr

Fix bogus pr31096-1.c failure for avr

The dump expects literals which would only be present if the target's
int size is 32 bits.

Fix by explicitly using 32 bit ints for targets with __SIZEOF_INT__ < 4.

gcc/testsuite/
2016-11-29  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>

	* testsuite/gcc.dg/pr31096-1.c: Use __{U,}INT32_TYPE__ for
	targets with sizeof(int) < 4.

From-SVN: r242954