builtin/difftool: plug memory leaks in run_dir_diff()

We're leaking a bunch of memory leaks in `run_dir_diff()`. Plug them.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

builtin/difftool.c

@@ -662,6 +662,9 @@ static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
 
 	free(lbase_dir);
 	free(rbase_dir);
+	strbuf_release(&info);
+	strbuf_release(&lpath);
+	strbuf_release(&rpath);
 	strbuf_release(&ldir);
 	strbuf_release(&rdir);
 	strbuf_release(&wtdir);