tools build: Fixup sched_getcpu feature test

Commit-ID:  1e6e7eae8a3a66f5fee4f44ef165ffcf31f0c40e
Gitweb:     http://git.kernel.org/tip/1e6e7eae8a3a66f5fee4f44ef165ffcf31f0c40e
Author:     Arnaldo Carvalho de Melo <[email protected]>
AuthorDate: Thu, 4 May 2017 10:30:40 -0300
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Thu, 4 May 2017 10:30:40 -0300

tools build: Fixup sched_getcpu feature test

We have tools/build/feature/test-all.c to speed up feature testing, doing all tests at once, but then all tests in this file should normally pass.

That is not the case with the sched-getcpu one, that wasn't passing when included from test-all.c because it needs to have _GNU_SOURCE defined before including sched.h, but _GNU_SOURCE is defined by a header included from another feature test included earlier in test-all.d, test-libpython.c, resulting in:

  $ cat /tmp/build/perf/feature/test-all.make.output
  In file included from test-all.c:121:0:
  test-sched_getcpu.c:1:0: error: "_GNU_SOURCE" redefined [-Werror]
   #define _GNU_SOURCE

In file included from /usr/include/python2.7/pyconfig.h:6:0,

                   from /usr/include/python2.7/Python.h:8,
                   from test-libpython.c:1,
                   from test-all.c:13:

/usr/include/python2.7/pyconfig-64.h:1177:0: note: this is the location of the previous definition
#define _GNU_SOURCE 1

cc1: all warnings being treated as errors

Which would trigger testing the tests individually, when that _GNU_SOURCE redefinition would not take place, and the whole process would continue, just slower... Fix it.

---
 tools/build/feature/test-sched_getcpu.c | 2 ++
 1 file changed, 2 insertions(+)

index c4a148d..9c6b4cb 100644
@@ -1,4 +1,6 @@
+#ifndef _GNU_SOURCE
 #define _GNU_SOURCE
+#endif
 #include <sched.h>
 
 int main(void)