Reduce parallel jobs in build_aar.py to 200 when building with goma.

Previously we were using 1024 parallel jobs. This is too much when
running on bots.

BUG=webrtc:7023
R=kjellander@webrtc.org
NOTRY=True

Review-Url: https://codereview.webrtc.org/2679123002
Cr-Commit-Position: refs/heads/master@{#16469}

tools-webrtc/android/build_aar.py

@@ -131,7 +131,7 @@ def Build(tmp_dir, arch, use_goma, extra_gn_args):
 
   ninja_args = TARGETS
   if use_goma:
-    ninja_args.extend(['-j', '1024'])
+    ninja_args.extend(['-j', '200'])
   _RunNinja(output_directory, ninja_args)