Do not use make clean for rubygem interception

This prevents an error when using scripts to install Sonic-Pi.

Author: bkmgit

app/server/ruby/bin/compile-extensions.rb

@@ -67,7 +67,9 @@
   puts "Compiling native extension in #{ext_dir}"
   Dir.chdir(ext_dir) do
     `"#{RbConfig.ruby}" extconf.rb`
-    `make clean`
+    if not (ext_dir.include? "interception")   
+      `make clean`
+    end
     `make`
   end