Revert "revert back to android-21 target until tinderbox gets updated"

Now it has been updated.

This reverts commit 4e47ed7e.

(cherry picked from commit 827e78fc)

android/Bootstrap/Makefile.shared

@@ -55,7 +55,7 @@ android_version_setup : $(BOOTSTRAPDIR)/no-resource-compress.xml
 prepare-appcompat:
 	mkdir $(APPCOMPATDIR) 2>/dev/null; true
 	cp -rf $(ANDROID_SDK_HOME)/extras/android/support/v7/appcompat/* $(APPCOMPATDIR)
-	$(ANDROID_SDK_HOME)/tools/android update lib-project --target android-21 --path $(APPCOMPATDIR)
+	$(ANDROID_SDK_HOME)/tools/android update lib-project --target android-23 --path $(APPCOMPATDIR)
 
 properties:
 	echo sdk.dir=$(ANDROID_SDK_HOME) >local.properties

android/Bootstrap/project.properties

@@ -9,4 +9,4 @@
 
 android.library=true
 # Project target.
-target=android-21
+target=android-23

android/source/project.properties

@@ -8,7 +8,7 @@
 # project structure.
 
 # Project target.
-target=android-21
+target=android-23
 
 # Use the Bootstrap class
 android.library.reference.1=../Bootstrap