soong: Make mkdir install dir optional

This prevents overriding commands error when device doesn't have it in
PRODUCT_PACKAGES.

Change-Id: Id4924ffe60d18ea54eb7c4dfa0d270ed2b00cef7
diff --git a/build/core/mkdir.mk b/build/core/mkdir.mk
index 01ab1f3..ada3931 100644
--- a/build/core/mkdir.mk
+++ b/build/core/mkdir.mk
@@ -18,13 +18,13 @@
 
 include $(BUILD_SYSTEM)/base_rules.mk
 
-$(LOCAL_SOONG_INSTALL_DIR):
-	@mkdir -p $@
-
-$(LOCAL_BUILT_MODULE): $(LOCAL_SOONG_INSTALL_DIR) $(LOCAL_ADDITIONAL_DEPENDENCIES)
+$(LOCAL_BUILT_MODULE): $(LOCAL_ADDITIONAL_DEPENDENCIES)
 	@mkdir -p $(dir $@)
 	@touch $@
 
 ifneq ($(filter $(LOCAL_MODULE),$(PRODUCT_PACKAGES)),)
+$(LOCAL_SOONG_INSTALL_DIR):
+	@mkdir -p $@
+
 ALL_DEFAULT_INSTALLED_MODULES += $(LOCAL_SOONG_INSTALL_DIR)
 endif