android: on prepare, clean all intermediates

This was requested to me to prevent no clobbered builds failures
on busybox config changes.

Change-Id: I1bdf2948e0669b1de567381eb809f576e8f1eef5

Android.mk

@@ -55,6 +55,7 @@ busybox_prepare_full := $(bb_gen)/full/.config
 $(busybox_prepare_full): $(BB_PATH)/busybox-full.config
 	@echo -e ${CL_YLW}"Prepare config for busybox binary"${CL_RST}
 	@rm -rf $(bb_gen)/full
+	@rm -rf $(TARGET_OUT_INTERMEDIATES)/EXECUTABLES/busybox_intermediates
 	@mkdir -p $(@D)
 	@cat $^ > $@ && echo "CONFIG_CROSS_COMPILER_PREFIX=\"$(BUSYBOX_CROSS_COMPILER_PREFIX)\"" >> $@
 	make -C $(BB_PATH) prepare O=$(@D) $(BB_PREPARE_FLAGS)
@@ -63,6 +64,7 @@ busybox_prepare_minimal := $(bb_gen)/minimal/.config
 $(busybox_prepare_minimal): $(BB_PATH)/busybox-minimal.config
 	@echo -e ${CL_YLW}"Prepare config for libbusybox"${CL_RST}
 	@rm -rf $(bb_gen)/minimal
+	@rm -rf $(TARGET_OUT_INTERMEDIATES)/STATIC_LIBRARIES/libbusybox_intermediates
 	@mkdir -p $(@D)
 	@cat $^ > $@ && echo "CONFIG_CROSS_COMPILER_PREFIX=\"$(BUSYBOX_CROSS_COMPILER_PREFIX)\"" >> $@
 	make -C $(BB_PATH) prepare O=$(@D) $(BB_PREPARE_FLAGS)