Refactor Android SDK installation script

Author: gnzlbg

ci/android-install-sdk.sh

@@ -19,6 +19,7 @@ set -ex
 # which apparently magically accepts the licenses.
 
 SDK=4333796
+API=26
 mkdir sdk
 curl --retry 10 https://dl.google.com/android/repository/sdk-tools-linux-${SDK}.zip -O
 unzip -d sdk sdk-tools-linux-${SDK}.zip
@@ -55,10 +56,10 @@ yes | ./sdk/tools/bin/sdkmanager --licenses --no_https
 yes | ./sdk/tools/bin/sdkmanager --no_https \
         "emulator" \
         "platform-tools" \
-        "platforms;android-26" \
-        "system-images;android-26;default;$abi"
+        "platforms;android-${API}" \
+        "system-images;android-${API};default;$abi"
 
 echo "no" |
     ./sdk/tools/bin/avdmanager create avd \
         --name "${1}" \
-        --package "system-images;android-26;default;$abi"
+        --package "system-images;android-${API};default;$abi"