Update references to build/core to build/make/core

sed -i -e 's"\([^/]\)build/core"\1build/make/core"g' $(git grep -l build/core)

Test: m checkbuild
Change-Id: Idf3a2fed79aee5d2c07bd8e42f0c0660f253ddc2
diff --git a/core/product-graph.mk b/core/product-graph.mk
index 36e9037..633ac37 100644
--- a/core/product-graph.mk
+++ b/core/product-graph.mk
@@ -34,7 +34,7 @@
 endef
 
 
-this_makefile := build/core/product-graph.mk
+this_makefile := build/make/core/product-graph.mk
 
 products_svg := $(OUT_DIR)/products.svg
 products_pdf := $(OUT_DIR)/products.pdf