Create parent directory before extracting symlink

At least when using Info-ZIP 3.0, symlinks to both files and directories
lack a trailing slash, so the second mz_path_remove_filename is
unnecessary (and could break things if the parent directory doesn't
precede the symlink in the file). If other implementations do add a
trailing slash, the if statement should handle that.

mz_zip_rw.c

@@ -721,7 +721,9 @@ int32_t mz_zip_reader_entry_save_file(void *handle, const char *path) {
     /* If symbolic link then properly construct destination path and link path */
     if (mz_zip_entry_is_symlink(reader->zip_handle) == MZ_OK) {
         mz_path_remove_slash(pathwfs);
-        mz_path_remove_filename(directory);
+        if (mz_zip_entry_is_dir(reader->zip_handle) == MZ_OK) {
+            mz_path_remove_filename(directory);
+        }
     }
 
     /* Create the output directory if it doesn't already exist */