Move ninja files to $(OUT_DIR)

Move the ninja files from $(PRODUCT_OUT)/build.ninja to
$(OUT_DIR)/build-$(TARGET_PRODUCT).ninja.  This will improve incremental
builds of host modules after swithing target products, because the
.ninja_deps file will be accurate across builds.

Change-Id: Ia12746ccde0de31f6fccd111b2bdbd48fc6900d7
1 file changed