dir: convert fill_directory to use the pathspec struct interface

Convert 'fill_directory()' to use the pathspec struct interface from
using the '_raw' entry in the pathspec struct.

Signed-off-by: Brandon Williams <bmwill@google.com>
Reviewed-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

dir.c

@@ -174,17 +174,21 @@ char *common_prefix(const struct pathspec *pathspec)
 
 int fill_directory(struct dir_struct *dir, const struct pathspec *pathspec)
 {
-	size_t len;
+	char *prefix;
+	size_t prefix_len;
 
 	/*
 	 * Calculate common prefix for the pathspec, and
 	 * use that to optimize the directory walk
 	 */
-	len = common_prefix_len(pathspec);
+	prefix = common_prefix(pathspec);
+	prefix_len = prefix ? strlen(prefix) : 0;
 
 	/* Read the directory and prune it */
-	read_directory(dir, pathspec->nr ? pathspec->_raw[0] : "", len, pathspec);
-	return len;
+	read_directory(dir, prefix, prefix_len, pathspec);
+
+	free(prefix);
+	return prefix_len;
 }
 
 int within_depth(const char *name, int namelen,