Fix oat-target-sync generated oat files to have leading /

Change-Id: I62321b05106c08e9e8cc15d2cadf8abee91ce568
diff --git a/Android.mk b/Android.mk
index 4086c2f..2dd2d8f 100644
--- a/Android.mk
+++ b/Android.mk
@@ -127,7 +127,7 @@
 define declare-oat-target-target
 .PHONY: oat-target-$(1)
 oat-target-$(1): $(PRODUCT_OUT)/$(1) $(TARGET_BOOT_IMG_OUT) $(DEX2OAT_DEPENDENCY)
-	$(DEX2OAT) --runtime-arg -Xms64m --runtime-arg -Xmx64m --boot-image=$(TARGET_BOOT_IMG_OUT) --dex-file=$(PRODUCT_OUT)/$(1) --dex-location=$(1) --oat-file=$(call art-cache-out,$(1).oat) --host-prefix=$(PRODUCT_OUT)
+	$(DEX2OAT) --runtime-arg -Xms64m --runtime-arg -Xmx64m --boot-image=$(TARGET_BOOT_IMG_OUT) --dex-file=$(PRODUCT_OUT)/$(1) --dex-location=/$(1) --oat-file=$(call art-cache-out,$(1).oat) --host-prefix=$(PRODUCT_OUT)
 
 OAT_TARGET_TARGETS += oat-target-$(1)
 endef