8159047: Disable redundant build steps when creating buildjdk

Reviewed-by: tbell, dholmes

make/Main.gmk

@@ -65,6 +65,9 @@ ALL_MODULES := $(call FindAllModules)
 ################################################################################
 # Interim/build tools targets, compiling tools used during the build
 
+# When creating a BUILDJDK, the buildtools and interim targets have already
+# been built and should not be built again.
+ifneq ($(CREATING_BUILDJDK), true)
   buildtools-langtools:
 	+($(CD) $(LANGTOOLS_TOPDIR)/make && $(MAKE) $(MAKE_ARGS) -f Tools.gmk)
 
@@ -79,6 +82,7 @@ interim-cldrconverter:
 
   buildtools-jdk:
 	+($(CD) $(JDK_TOPDIR)/make && $(MAKE) $(MAKE_ARGS) -f CompileTools.gmk)
+endif
 
 ALL_TARGETS += buildtools-langtools interim-langtools \
     interim-rmic interim-cldrconverter buildtools-jdk
@@ -99,6 +103,10 @@ ALL_TARGETS += import-hotspot unpack-sec generate-exported-symbols
 
 ################################################################################
 # Gensrc targets, generating source before java compilation can be done
+#
+# When creating a BUILDJDK, the java targets have already been built and copied
+# into the buildjdk so no need to generate sources.
+ifneq ($(CREATING_BUILDJDK), true)
   $(eval $(call DeclareRecipesForPhase, GENSRC, \
       TARGET_SUFFIX := gensrc, \
       FILE_PREFIX := Gensrc, \
@@ -128,6 +136,7 @@ define DeclareModuleInfoRecipe
   endef
 
   $(foreach m, $(GENSRC_MODULEINFO_MODULES), $(eval $(call DeclareModuleInfoRecipe,$m)))
+endif
 
 ALL_TARGETS += $(GENSRC_TARGETS)