Add Android sound and music to source code, and avoid building them o…

…n F-Droid

by using a special android-pre-fdroid target that assumes they are
already there.

.gitignore

@@ -14,7 +14,7 @@ recordings/
 
 # Android
 rabbit-escape-ui-android/app/libs/rabbit-escape-generic.jar
-rabbit-escape-ui-android/app/src/main/assets/
+rabbit-escape-ui-android/app/src/main/assets/images*
 rabbit-escape-ui-android/app/src/main/res/drawable-mdpi/*.png
 rabbit-escape-ui-android/app/src/main/res/drawable-hdpi/*.png
 rabbit-escape-ui-android/app/src/main/res/drawable-xhdpi/*.png

Makefile

@@ -376,6 +376,12 @@ android-pre: \
 	android-music \
 	rabbit-escape-ui-android/app/libs/rabbit-escape-generic.jar
 
+# Special target for F-Droid that does not build the sound or music files,
+# to avoid needing sox to be installed on the F-Droid server.
+android-pre-fdroid: \
+	android-images \
+	rabbit-escape-ui-android/app/libs/rabbit-escape-generic.jar
+
 android-compile: android-pre
 	@echo ". Compiling Android code"
 	@cd rabbit-escape-ui-android && \