Issue #147: Support module-path for ECJ

Simply add the path from the CompilerConfiguration to the command-line
arguments.

Author: tomaswolf

plexus-compilers/plexus-compiler-eclipse/src/main/java/org/codehaus/plexus/compiler/eclipse/EclipseJavaCompiler.java

@@ -229,6 +229,13 @@ public CompilerResult performCompile( CompilerConfiguration config )
         args.add( "-classpath" );
         args.add( getPathString( classpathEntries ) );
 
+        List<String> modulepathEntries = config.getModulepathEntries();
+        if ( modulepathEntries != null && !modulepathEntries.isEmpty() )
+        {
+            args.add( "--module-path" );
+            args.add( getPathString( modulepathEntries ) );
+        }
+
         // Collect sources
         List<String> allSources = new ArrayList<>();
         for ( String source : config.getSourceLocations() )