perf tools: No need to test against NULL before calling free()

Its perfectly fine to call free(NULL), so no need to clutter the source
code with all those superfluous testing.

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-uux5wpvevlerd42gqer13e7n@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/browsers/scripts.c

@@ -173,8 +173,7 @@ int script_browse(const char *script_opt)
 	if (script.b.width > AVERAGE_LINE_LEN)
 		script.b.width = AVERAGE_LINE_LEN;
 
-	if (line)
-		free(line);
+	free(line);
 	pclose(fp);
 
 	script.nr_lines = nr_entries;