6954901: langtools/test/Makefile should check for bin/javac(.exe) instead of lib/tools.jar

Reviewed-by: ohair

test/Makefile

@@ -50,6 +50,7 @@ ifeq ($(OSNAME), Windows_NT)
       endif
     endif
   endif
+  EXE_SUFFIX=.exe
 endif
 
 # Root of this test area (important to use full paths in some places)
@@ -105,12 +106,13 @@ endif
 # PRODUCT_HOME is a JPRT variable pointing to a directory containing the output from 
 # make/Makefile
 # For langtools, this is a directory containing build and dist
-# For a control build, this is build/$(PRODUCT)-$(ARCH)/j2sdk-image
+# For a control build, this is build/$(PRODUCT)-$(ARCH)/XYZ-image 
+#	(i.e, j2sdk-image or jdk-module-image)
 ifdef PRODUCT_HOME
   ifeq ($(shell [ -r $(PRODUCT_HOME)/dist/lib/classes.jar ]; echo $$?),0)
     TESTBOOTCLASSPATH = $(PRODUCT_HOME)/dist/lib/classes.jar
   endif
-  ifeq ($(shell [ -r $(PRODUCT_HOME)/lib/tools.jar ]; echo $$?),0)
+  ifeq ($(shell [ -r $(PRODUCT_HOME)/bin/javac$(EXE_SUFFIX) ]; echo $$?),0)
     TESTJAVA = $(PRODUCT_HOME)
   endif
 endif