Gatekeeper workaround is no more needed with avrdude linked statically

See:

arduino/avrdude-build-script@2db1e51
arduino/avrdude-build-script@960dfb9

Author: cmaglie

build/build.xml

@@ -494,11 +494,6 @@
       <fileset dir="${staging_folder}/work/${staging_hardware_folder}/tools" includes="**/bin/*"/>
       <fileset dir="${staging_folder}/work/${staging_hardware_folder}/tools" includes="**/libexec/gcc/avr/4.8.1/*"/>
     </chmod>
-
-    <!-- macosx gatekeeper workaround. See https://github.com/arduino/Arduino/issues/3468 -->
-    <chmod perm="-x">
-      <fileset dir="${staging_folder}/work/${staging_hardware_folder}/tools" includes="**/bin/avrdude_bin" />
-    </chmod>
   </target>
 
   <target name="macosx-run" depends="build,start"/>