Fix 'gcc.dg/pr110279-2.c' syntax error due to '__attribute_noinline__'

Fix 'gcc.dg/pr110279-2.c' syntax error due to '__attribute_noinline__'

For example, for GCN or nvptx target configurations, using newlib:

    FAIL: gcc.dg/pr110279-2.c (test for excess errors)
    UNRESOLVED: gcc.dg/pr110279-2.c scan-tree-dump-not reassoc2 "was chosen for reassociation"
    UNRESOLVED: gcc.dg/pr110279-2.c scan-tree-dump-times optimized "\\.FMA " 3

    [...]/source-gcc/gcc/testsuite/gcc.dg/pr110279-2.c:11:1: error: unknown type name '__attribute_noinline__'
    [...]/source-gcc/gcc/testsuite/gcc.dg/pr110279-2.c:12:1: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'foo'

We cannot assume 'stdio.h' to define '__attribute_noinline__' -- but then, that
also isn't necessary for this test case (there is nothing to inline into).

	gcc/testsuite/
	* gcc.dg/pr110279-2.c: Don't '#include <stdio.h>'.  Remove
	'__attribute_noinline__'.