perf probe: Avoid accessing uninitialized 'map' variable

Genuine problem detected with clang, the warnings are spot on:

util/probe-event.c:2079:7: error: variable 'map' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
if (addr) {
^~~~
util/probe-event.c:2094:6: note: uninitialized use occurs here
if (map && !is_kprobe) {
^~~
util/probe-event.c:2079:3: note: remove the 'if' if its condition is always true
if (addr) {
^~~~~~~~~~
util/probe-event.c:2075:8: error: variable 'map' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
if (kernel_get_symbol_address_by_name(tp->symbol,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
util/probe-event.c:2094:6: note: uninitialized use occurs here
if (map && !is_kprobe) {
^~~
util/probe-event.c:2075:4: note: remove the 'if' if its condition is always false
if (kernel_get_symbol_address_by_name(tp->symbol,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
util/probe-event.c:2064:17: note: initialize the variable 'map' to silence this warning
struct map *map;
^
= NULL

Cc: Adrian Hunter <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Masami Hiramatsu <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/probe-event.c

···
 					  bool is_kprobe)
 {
 	struct symbol *sym = NULL;
-	struct map *map;
+	struct map *map = NULL;
 	u64 addr = tp->address;
 	int ret = -ENOENT;