stdio-common/tst-printf-bz18872.sh: Use attribute optimize instead of

This fixes build problems on arm, aarch64 and s390, which failed due to
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59884.

ChangeLog

@@ -1,3 +1,8 @@
+2015-10-07  Paul Pluzhnikov  <ppluzhnikov@google.com>
+
+	* stdio-common/tst-printf-bz18872.sh: Use attribute optimize
+	instead of #pragma optimize.
+
 2015-10-07  Carlos O'Donell  <carlos@redhat.com>
 
 	[BZ #17195]

stdio-common/tst-printf-bz18872.sh

@@ -30,9 +30,8 @@ cat <<'EOF'
 /*
   Compile do_test without optimization: GCC 4.9/5.0/6.0 takes a long time
   to build this source. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67396  */
-#pragma GCC push_options
-#pragma GCC optimize ("-O0")
 
+__attribute__ ((optimize ("-O0")))
 int do_test (void)
 {
     mtrace ();
@@ -62,7 +61,6 @@ cat <<'EOF'
 
   return 0;
 }
-#pragma GCC pop_options
 
 #define TEST_FUNCTION do_test ()
 #include "../test-skeleton.c"