add the the previously deleted build-tools.

Michael created

Change summary

.travis.yml | 3 +++
1 file changed, 3 insertions(+)

Detailed changes

.travis.yml 🔗

@@ -4,5 +4,8 @@ android:
     - platform-tools
     - tools
     - build-tools-23.0.0
+    - build-tools-22.0.1
+    - build-tools-21.1.2
+    - build-tools-19.1.0
     - android-23
     - extra-android-m2repository