Fix failing overflow-1.c for avr

Fix failing overflow-1.c for avr

The test assumes 32 bit ints, and expects a constant in the
dump that is only valid for 32 bit ints. Fix by explicitly
specifying __UINT32_TYPE__.

gcc/testsuite/

2017-03-21  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>

	* gcc.dg/tree-ssa/overflow-1.c: Use __UINT32_TYPE__ for targets
	with sizeof(int) < 4.

From-SVN: r246318