ruby: get rid of ruby's Debug.hh

Get rid of the Debug class
Get rid of ASSERT and use assert
Use DPRINTFR for ProtocolTrace

src/mem/SConscript

@@ -60,6 +60,7 @@ TraceFlag('LLSC')
 TraceFlag('MMU')
 TraceFlag('MemoryAccess')
 
+TraceFlag('ProtocolTrace')
 TraceFlag('RubyCache')
 TraceFlag('RubyDma')
 TraceFlag('RubyGenerated')