Add third_party/apple_apsl to get Mac build working

Change-Id: I8ee2e50e21f63dfcd5b1271193189fdfa76cf834
Reviewed-on: https://gn-review.googlesource.com/1120
Reviewed-by: Scott Graham <scottmg@chromium.org>
Reviewed-by: Petr Hosek <phosek@google.com>
Commit-Queue: Scott Graham <scottmg@chromium.org>
diff --git a/.gitignore b/.gitignore
index 8c85b91..ae30641 100644
--- a/.gitignore
+++ b/.gitignore
@@ -44,6 +44,7 @@
 .pydevproject
 .checkstyle
 cscope.*
+out/
 GPATH
 GRTAGS
 GSYMS