tools build: Make fixdep parsing wait for last target

The fixdep tool, among other things, replaces the target of the object
in the gcc generated dependency output file.

The parsing code assumes there's only single target in the rule but this
is not always the case as described in here:

  https://gcc.gnu.org/ml/gcc-help/2016-11/msg00099.html

Make the fixdep code smart enough to skip all the possible targets.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Peter Foley <pefoley2@pefoley.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20161201130025.GA16430@kravaSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/build/fixdep.c

@@ -49,7 +49,7 @@ static void parse_dep_file(void *map, size_t len)
 	char *end = m + len;
 	char *p;
 	char s[PATH_MAX];
-	int is_target;
+	int is_target, has_target = 0;
 	int saw_any_target = 0;
 	int is_first_dep = 0;
 
@@ -67,7 +67,8 @@ static void parse_dep_file(void *map, size_t len)
 		if (is_target) {
 			/* The /next/ file is the first dependency */
 			is_first_dep = 1;
-		} else {
+			has_target = 1;
+		} else if (has_target) {
 			/* Save this token/filename */
 			memcpy(s, m, p-m);
 			s[p - m] = 0;