Fix JRUBY-4738: test/testapp/testapp.exe appears twice in jruby-src-1…

….5.0.RC1.tar.gz

Exclude test/testapp/testapp and test/testapp/testapp.exe that are included later in the build process

build.xml

@@ -1240,6 +1240,8 @@
     <include name="bench/**"/>
     <include name="src/**"/>
     <include name="test/**"/>
+    <exclude name="test/testapp/testapp"/>
+    <exclude name="test/testapp/testapp.exe"/>
     <include name="spec/**"/>
     <exclude name="spec/mspec"/>
     <exclude name="spec/ruby"/>