8157030: langtools dev build broken after classfile version bump

Fix build to use different source/target version when compiling build tools

Reviewed-by: jlahoda

langtools/make/build.properties

@@ -28,6 +28,10 @@ javac.opts = -XDignore.symbol.file=true -Xlint:all,-deprecation,-options -Werror
 javac.source = 9
 javac.target = 9
 
+#version used to compile build tools
+javac.build.source = 8
+javac.build.target = 8
+
 langtools.resource.includes = \
         com/sun/tools/javac/resources/compiler.properties
 

langtools/make/build.xml

@@ -243,7 +243,9 @@
         <replace file=".idea/workspace.xml" token="@XPATCH@" value="${xpatch.cmd}"/>
         <replace file=".idea/workspace.xml" token="@PATH_SEP@" value="${path.separator}"/>
         <mkdir dir=".idea/classes"/>
-        <javac srcdir="make/intellij/src"
+        <javac source="${javac.build.source}"
+               target="${javac.build.target}"
+               srcdir="make/intellij/src"
                destdir=".idea/classes"/>
     </target>
 
@@ -255,10 +257,8 @@
         <copy todir="${build.tools}/propertiesparser" >
             <fileset dir="${make.tools.dir}/propertiesparser" includes="**/resources/**"/>
         </copy>
-        <javac fork="true"
-               source="${javac.source}"
-               target="${javac.target}"
-               executable="${langtools.jdk.home}/bin/javac"
+        <javac source="${javac.build.source}"
+               target="${javac.build.target}"
                srcdir="${make.tools.dir}"
                includes="propertiesparser/* anttasks/PropertiesParser* anttasks/PathFileSet*"
                destdir="${build.tools}"
@@ -273,10 +273,9 @@
     </target>
 
      <target name="-def-pcompile">
-        <javac fork="true"
-               source="${javac.source}"
-               target="${javac.target}"
-               executable="${langtools.jdk.home}/bin/javac"
+        <javac
+               source="${javac.build.source}"
+               target="${javac.build.target}"
                srcdir="${make.tools.dir}"
                includes="compileproperties/* anttasks/CompileProperties* anttasks/PathFileSet*"
                destdir="${build.dir}/toolclasses/"