perf tools: Bool functions shouldn’t return -1

Author: Peter Senna Tschudin <peter.senna@gmail.com>

Returning a negative value for a boolean function seem to have the
undesired effect of returning true. Replace -1 by false in a
bool-returning function.

The diff of the .s file before and after the change (for x86_64):

  3907c3907
  < 	movl	$1, %ebx
  ---
  > 	xorl	%ebx, %ebx

while if -1 is replaced by true, the diff is empty.

This issue was found by the following Coccinelle semantic patch:

  
  @@
  identifier f;
  constant C;
  typedef bool;
  @@
  bool f (...){
  <+...
  * return -C;
  ...+>
  }
  

Signed-off-by: Peter Senna Tschudin 
Cc: Jiri Olsa 
Cc: Kan Liang 
Cc: Matt Fleming 
Cc: Milos Vyletel 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Link: http://lkml.kernel.org/r/1442484533-19742-1-git-send-email-peter.senna@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo 

---
 tools/perf/util/util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 7acafb3..c2cd9bf2 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -709,7 +709,7 @@ bool find_process(const char *name)
 
 	dir = opendir(procfs__mountpoint());
 	if (!dir)
-		return -1;
+		return false;
 
 	/* Walk through the directory. */
 	while (ret && (d = readdir(dir)) != NULL) {