Fix broken attr-alloc_size-10.c for avr

Integer promotion combined with equal sizes for short and int (16 bits)
causes overflow warnings when expanding the TEST macro for USHRT_MAX.

Fix by explicitly disabling overflow warnings for targets with !int32plus.

gcc/testsuite/

2017-04-25  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>

	* gcc.dg/attr-alloc_size-10.c: Ignore overflow warnings
	for targets with int size less than 32 bits.

From-SVN: r247203

gcc/testsuite/ChangeLog

+2017-04-25  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
+
+	* gcc.dg/attr-alloc_size-10.c: Ignore overflow warnings
+	for targets with int size less than 32 bits.
+
 2017-04-25  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/79201

gcc/testsuite/gcc.dg/attr-alloc_size-10.c

@@ -4,7 +4,8 @@
    range.
 
    { dg-do compile }
-   { dg-options "-O2 -Walloc-size-larger-than=12" } */
+   { dg-options "-O2 -Walloc-size-larger-than=12" } 
+   { dg-options "-Wno-overflow" { target { ! int32plus } } } */
 
 #define SCHAR_MAX __SCHAR_MAX__
 #define SCHAR_MIN (-SCHAR_MAX - 1)