Move booting to RubyXCompiler init

Also pass the source into the compile method.
This way compiler can be reused for subsequent compile.
Does remove some double boots, but no major time save

test/risc/test_linker.rb

@@ -19,7 +19,7 @@ module Risc
   end
   class TestLinkerInit < MiniTest::Test
     def setup
-      @linker = RubyX::RubyXCompiler.new("class Space;def main;return 1;end;end").ruby_to_binary(:arm)
+      @linker = RubyX::RubyXCompiler.new.ruby_to_binary("class Space;def main;return 1;end;end",:arm)
     end
     def test_pos_cpu
       assert_equal 0 ,  Position.get(@linker.cpu_init).at