Ensure directories in the Soong output dir have appropriate permissions, so that 'm clean' works.

In particular, Bazel sometimes creates directories whose files cannot be deleted.

Test: m clean used to fail after b build //system/timezone/apex:com.android.tzdata, but now it works
Test: Added integration test which fails without this change

Change-Id: I08c8feed21c31ec187fe40be513f7eb4865c8ac3
diff --git a/tests/run_integration_tests.sh b/tests/run_integration_tests.sh
index 8399573..6304a11 100755
--- a/tests/run_integration_tests.sh
+++ b/tests/run_integration_tests.sh
@@ -6,3 +6,4 @@
 "$TOP/build/soong/tests/bootstrap_test.sh"
 "$TOP/build/soong/tests/mixed_mode_test.sh"
 "$TOP/build/soong/tests/bp2build_bazel_test.sh"
+"$TOP/build/soong/tests/soong_test.sh"