8157506: Disable bootcycle build when cross compiling

Reviewed-by: alanb, tbell, mchung
diff --git a/make/Main.gmk b/make/Main.gmk
index b0361fb..cbde81f 100644
--- a/make/Main.gmk
+++ b/make/Main.gmk
@@ -302,9 +302,13 @@
 
 BOOTCYCLE_TARGET := product-images
 bootcycle-images:
-	@$(ECHO) Boot cycle build step 2: Building a new JDK image using previously built image
-	+$(MAKE) -f $(SRC_ROOT)/make/Init.gmk PARALLEL_TARGETS=$(BOOTCYCLE_TARGET) \
-	    JOBS= SPEC=$(dir $(SPEC))bootcycle-spec.gmk main
+        ifneq ($(COMPILE_TYPE), cross)
+	  $(call LogWarn, Boot cycle build step 2: Building a new JDK image using previously built image)
+	  +$(MAKE) -f $(SRC_ROOT)/make/Init.gmk PARALLEL_TARGETS=$(BOOTCYCLE_TARGET) \
+	      JOBS= SPEC=$(dir $(SPEC))bootcycle-spec.gmk main
+        else
+	  $(call LogWarn, Boot cycle build disabled when cross compiling)
+        endif
 
 zip-security:
 	+($(CD) $(SRC_ROOT)/make && $(MAKE) $(MAKE_ARGS) -f ZipSecurity.gmk)