Only install emulators if they’re used by the build matrix.

.travis.yml

@@ -9,10 +9,6 @@ android:
   - tools
   - build-tools-26.0.1
   - android-26
-  - android-22
-  - android-16
-  - sys-img-armeabi-v7a-android-22
-  - sys-img-armeabi-v7a-android-16
 
 licenses:
   - 'android-sdk-license.*'

scripts/travis_create_emulator.sh

@@ -2,6 +2,8 @@
 
 set -e
 
+echo y | android --silent update sdk --no-ui --all --filter android-$ANDROID_TARGET
+echo y | android --silent update sdk --no-ui --all --filter sys-img-armeabi-v7a-android-$ANDROID_TARGET
 echo no | android create avd --force -n test -t android-$ANDROID_TARGET --abi armeabi-v7a
 QEMU_AUDIO_DRV=none emulator -engine classic -avd test -no-window &