RFR: JDK-8144911: Consider having modifications to jdk.jlink trigger recreation of all jmods

[Erik Joelsson]

This small patch adds the jmod tool itself as a dependency to the 
creation of jmods. The effect of this is that changes to the jmod tool 
src will trigger a rebuild of all jmods automatically.

Bug: https://bugs.openjdk.java.net/browse/JDK-8144911
Patch:
diff -r 89769a2f1511 make/CreateJmods.gmk
--- a/make/CreateJmods.gmk
+++ b/make/CreateJmods.gmk
@@ -82,6 +82,12 @@
    endif
  endif

+# Changes to the jmod tool itself should also trigger a rebuild of all 
jmods
+DEPS += $(JMOD_CMD)
+ifeq ($(EXTERNAL_BUILDJDK), false)
+  DEPS += $(call CacheFind, 
$(JDK_OUTPUTDIR)/modules/jdk.jlink/jdk/tools/jmod)
+endif
+
  # TODO: What about headers?
  # Create jmods in a temp dir and then move them into place to keep the
  # module path in $(IMAGES_OUTPUTDIR)/jmods valid at all times.


/Erik