perf_counter tools: Introduce stricter C code checking

Tighten up our C code requirements:

 - disallow warnings
 - disallow declarations-mixed-with-statements
 - require proper prototypes
 - require C99 (with gcc extensions)

Fix up a ton of problems these measures unearth:

 - unused functions
 - needlessly global functions
 - missing prototypes
 - code mixed with declarations

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090526222155.GJ4424@ghostprotocols.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/Documentation/perf_counter/util/abspath.c b/Documentation/perf_counter/util/abspath.c
index 649f34f..61d33b8 100644
--- a/Documentation/perf_counter/util/abspath.c
+++ b/Documentation/perf_counter/util/abspath.c
@@ -5,7 +5,7 @@
  * symlink to a directory, we do not want to say it is a directory when
  * dealing with tracked content in the working tree.
  */
-int is_directory(const char *path)
+static int is_directory(const char *path)
 {
 	struct stat st;
 	return (!stat(path, &st) && S_ISDIR(st.st_mode));