fixdep: fix CONFIG_IS_ENABLED etc. handling

When fixdep detects CONFIG_IS_ENABLED and other similar macros, it must
parse the macro parameter to determine which actual CONFIG_ option is
being referenced. This involves moving a pointer forward through the
entire CONFIG_ option "word". Currently, the code uses variable q to walk
through the word, but doesn't actually initialize it to point at the
parameter before doing so. Consequently, the walking process immediately
fails since it sees the macro invocatoins's ( rather than the expected
alpha-numeric characters in the macro parameter. Fix this by adding the
missing initialization.

Fixes: 67f2ee8 ("kbuild: fixdep: Resync this with v4.17")
Fixes: 7012865 ("gpio: fix test.py for gpio label lookup")
Signed-off-by: Stephen Warren <[email protected]>
Reviewed-by: Simon Glass <[email protected]>

scripts/basic/fixdep.c

@@ -266,6 +266,7 @@ static void parse_config_file(const char *p)
 		    (q - p == 9 && !memcmp(p, "IS_MODULE(", 10)) ||
 		    (q - p == 3 && !memcmp(p, "VAL(", 4))) {
 			p = q + 1;
+			q  = p;
 			while (isalnum(*q) || *q == '_')
 				q++;
 			r = q;