Restrict dex2oat threads to 4 on android bots.

Test: manaul
Bug: 64686163
Change-Id: I81c7a4c9ac586b9dc0acf52a45955d4d7a3c9daa
diff --git a/test/testrunner/run_build_test_target.py b/test/testrunner/run_build_test_target.py
index b1274c9..49444d4 100755
--- a/test/testrunner/run_build_test_target.py
+++ b/test/testrunner/run_build_test_target.py
@@ -100,6 +100,8 @@
   run_test_command += ['-b']
   run_test_command += ['--host']
   run_test_command += ['--verbose']
+  run_test_command += ['--dex2oat-jobs']
+  run_test_command += ['4']
 
   sys.stdout.write(str(run_test_command) + '\n')
   sys.stdout.flush()