Restricting the shared lib to java 7

Bug: 112849320
Test: Verified launcher works fine with the new jar
Change-Id: Ibfbc4e53f879894ada134c227e212e3e23c49ea6
diff --git a/packages/SystemUI/shared/Android.bp b/packages/SystemUI/shared/Android.bp
index 0fb1200..eb71698 100644
--- a/packages/SystemUI/shared/Android.bp
+++ b/packages/SystemUI/shared/Android.bp
@@ -20,6 +20,9 @@
         "src/**/I*.aidl",
     ],
 
+    // Enforce that the library is build agains java 7 so that there are
+    // no compatibility issues with launcher
+    java_version: "1.7",
 }
 
 android_app {