src: fix compiler warnings

The warnings in question are:

../src/node.cc:844:13: warning:
unused function 'DebugProcess' [-Wunused-function]
static void DebugProcess(const FunctionCallbackInfo<Value>& args);
            ^
../src/node.cc:845:13: warning:
unused function 'DebugEnd' [-Wunused-function]
static void DebugEnd(const FunctionCallbackInfo<Value>& args);

PR-URL: nodejs#25165
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>

src/node.cc

@@ -852,9 +852,6 @@ static Local<Object> GetFeatures(Environment* env) {
   return scope.Escape(obj);
 }
 
-static void DebugProcess(const FunctionCallbackInfo<Value>& args);
-static void DebugEnd(const FunctionCallbackInfo<Value>& args);
-
 void SetupProcessObject(Environment* env,
                         const std::vector<std::string>& args,
                         const std::vector<std::string>& exec_args) {