8168663: Nashorn: ant testng tests doesn't support external java options

Added new run.test.jvmargs.external property

Reviewed-by: sundar, hannesw

nashorn/make/build.xml

@@ -28,6 +28,10 @@
   <import file="code_coverage.xml"/>
 
   <target name="load-properties">
+    <!-- set default values to run.test.jvmargs.external property -->
+    <condition property="run.test.jvmargs.external" value="">
+     <not><isset property="run.test.jvmargs.external"/></not>
+    </condition>     
     <!-- loading locally defined resources and properties. NB they owerwrite default ones defined later -->
     <property file="${user.home}/.nashorn.project.local.properties"/>
 

nashorn/make/project.properties

@@ -355,6 +355,7 @@ run.test.user.country=TR
 run.test.jvmargs.common=\
   -server \
   ${test.module.imports} \
+  ${run.test.jvmargs.external} \
   ${nashorn.override.option} \
   -Dfile.encoding=UTF-8 \
   -Duser.language=${run.test.user.language} \