perf tools: Introduce zfree

For the frequent idiom of:

   free(ptr);
   ptr = NULL;

Make it expect a pointer to the pointer being freed, so that it becomes
clear at first sight that the variable being freed is being modified.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-pfw02ezuab37kha18wlut7ir@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 8c08735..6d8796e 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -226,10 +226,8 @@
 	if (!dbg)
 		return NULL;
 
-	if (debuginfo__init_offline_dwarf(dbg, path) < 0) {
-		free(dbg);
-		dbg = NULL;
-	}
+	if (debuginfo__init_offline_dwarf(dbg, path) < 0)
+		zfree(&dbg);
 
 	return dbg;
 }
@@ -241,10 +239,8 @@
 	if (!dbg)
 		return NULL;
 
-	if (debuginfo__init_online_kernel_dwarf(dbg, (Dwarf_Addr)addr) < 0) {
-		free(dbg);
-		dbg = NULL;
-	}
+	if (debuginfo__init_online_kernel_dwarf(dbg, (Dwarf_Addr)addr) < 0)
+		zfree(&dbg);
 
 	return dbg;
 }
@@ -1302,8 +1298,7 @@
 
 	ret = debuginfo__find_probes(dbg, &tf.pf);
 	if (ret < 0) {
-		free(*tevs);
-		*tevs = NULL;
+		zfree(tevs);
 		return ret;
 	}
 
@@ -1417,8 +1412,7 @@
 			free(af.vls[af.nvls].point.symbol);
 			strlist__delete(af.vls[af.nvls].vars);
 		}
-		free(af.vls);
-		*vls = NULL;
+		zfree(vls);
 		return ret;
 	}
 
@@ -1522,8 +1516,7 @@
 	if (fname) {
 		ppt->file = strdup(fname);
 		if (ppt->file == NULL) {
-			free(ppt->function);
-			ppt->function = NULL;
+			zfree(&ppt->function);
 			ret = -ENOMEM;
 			goto end;
 		}
@@ -1577,8 +1570,7 @@
 		else
 			ret = 0;	/* Lines are not found */
 	else {
-		free(lf->lr->path);
-		lf->lr->path = NULL;
+		zfree(&lf->lr->path);
 	}
 	return ret;
 }