config: properly handle multiline quotes

Pass a pointer to the quote counts so that we can increment it.

src/libgit2/config_parse.c

@@ -279,8 +279,7 @@ static int skip_bom(git_parse_ctx *parser)
 */
 
 /* '\"' -> '"' etc */
-static int unescape_line(
-	char **out, bool *is_multi, const char *ptr, int quote_count)
+static int unescape_line(char **out, bool *is_multi, const char *ptr, int *quote_count)
 {
 	char *str, *fixed, *esc;
 	size_t ptr_len = strlen(ptr), alloc_len;
@@ -296,7 +295,8 @@ static int unescape_line(
 
 	while (*ptr != '\0') {
 		if (*ptr == '"') {
-			quote_count++;
+			if (quote_count)
+				(*quote_count)++;
 		} else if (*ptr != '\\') {
 			*fixed++ = *ptr;
 		} else {
@@ -358,7 +358,7 @@ static int parse_multiline_variable(git_config_parser *reader, git_str *value, i
 			goto next;
 
 		if ((error = unescape_line(&proc_line, &multiline,
-					   line, in_quotes)) < 0)
+					   line, &in_quotes)) < 0)
 			goto out;
 
 		/* Add this line to the multiline var */
@@ -445,7 +445,7 @@ static int parse_variable(git_config_parser *reader, char **var_name, char **var
 		while (git__isspace(value_start[0]))
 			value_start++;
 
-		if ((error = unescape_line(&value, &multiline, value_start, 0)) < 0)
+		if ((error = unescape_line(&value, &multiline, value_start, NULL)) < 0)
 			goto out;
 
 		if (multiline) {