builtin/config.c: Fix a sparse warning

Sparse issues an "Using plain integer as NULL pointer" warning while
checking a 'struct strbuf_list' initializer expression. The initial
field of the struct has pointer type, but the initializer expression
is given as '{0}'. In order to suppress the warning, we simply replace
the initializer with '{NULL}'.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Jeff King <peff@peff.net>

builtin/config.c

@@ -165,7 +165,7 @@ static int collect_config(const char *key_, const char *value_, void *cb)
 static int get_value(const char *key_, const char *regex_)
 {
 	int ret = CONFIG_GENERIC_ERROR;
-	struct strbuf_list values = {0};
+	struct strbuf_list values = {NULL};
 	int i;
 
 	if (use_key_regexp) {