android: Add a missing dependency.

Useful when you switch sdk to a different location.

Change-Id: I95301cc9adf50a0bbd918cc7562b8871093625b8
Reviewed-on: https://gerrit.libreoffice.org/67873
Tested-by: Jenkins
Reviewed-by: Jan Holesovsky <kendy@collabora.com>

android/Bootstrap/Makefile.shared

@@ -21,7 +21,7 @@ OBJLOCAL=obj/local/$(ANDROID_APP_ABI)
 # Helpful rules ...
 #
 
-local.properties:
+local.properties: $(BUILDDIR)/config_host.mk
 	echo sdk.dir=$(ANDROID_SDK_HOME) >local.properties
 
 #