fix system size calculation for SDK build

The SDK build doesn't have recovery, don't try to generate a patch or
include it in the system image size calculation.  Also there's a
dependency on bsdiff that was omitted.
diff --git a/core/Makefile b/core/Makefile
index c723898..656a663 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -646,14 +646,19 @@
 # as the source (since they are very similar).  Generate the patch so
 # we can see how big it's going to be, and include that in the system
 # image size check calculation.
+ifneq ($(TARGET_PRODUCT),sdk)
 intermediates := $(call intermediates-dir-for,PACKAGING,recovery_patch)
 RECOVERY_FROM_BOOT_PATCH := $(intermediates)/recovery_from_boot.p
 $(RECOVERY_FROM_BOOT_PATCH): $(INSTALLED_RECOVERYIMAGE_TARGET) \
                              $(INSTALLED_BOOTIMAGE_TARGET) \
-			     | $(HOST_OUT_EXECUTABLES)/imgdiff
+			     | $(HOST_OUT_EXECUTABLES)/imgdiff \
+	                       $(HOST_OUT_EXECUTABLES)/bsdiff
 	@echo "Construct recovery from boot"
 	mkdir -p $(dir $@)
 	$(HOST_OUT_EXECUTABLES)/imgdiff $(INSTALLED_BOOTIMAGE_TARGET) $(INSTALLED_RECOVERYIMAGE_TARGET) $@
+else  # TARGET_PRODUCT == sdk
+RECOVERY_FROM_BOOT_PATCH :=
+endif
 
 $(INSTALLED_SYSTEMIMAGE): $(BUILT_SYSTEMIMAGE) $(RECOVERY_FROM_BOOT_PATCH) | $(ACP)
 	@echo "Install system fs image: $@"