Don't try to apply --build-dir to standalone projects.

Fixes build_dir test failure on linux.


[SVN r39194]

tools/build

@@ -1 +1 @@
-Subproject commit bcc1770d0810a0de3830155d7f5c5dbee41e0c51
+Subproject commit ef24b573cff880a0727d48176f50f357ef0e3190