Fix compilation warning in Ninja's test suite.

Author: nicolasdespres

src/build_test.cc

@@ -251,7 +251,7 @@ bool BuildTest::StartCommand(Edge* edge) {
   return true;
 }
 
-Edge* BuildTest::WaitForCommand(bool* success, string* output) {
+Edge* BuildTest::WaitForCommand(bool* success, string* /* output */) {
   if (Edge* edge = last_command_) {
     if (edge->rule_->name_ == "fail")
       *success = false;

src/disk_interface_test.cc

@@ -163,15 +163,15 @@ struct StatTest : public StateTestWithBuiltinRules,
                   public DiskInterface {
   // DiskInterface implementation.
   virtual int Stat(const string& path);
-  virtual bool MakeDir(const string& path) {
+  virtual bool MakeDir(const string& /* path */) {
     assert(false);
     return false;
   }
-  virtual string ReadFile(const string& path, string* err) {
+  virtual string ReadFile(const string& /* path */, string* /* err */) {
     assert(false);
     return "";
   }
-  virtual int RemoveFile(const string& path) {
+  virtual int RemoveFile(const string& /* path */) {
     assert(false);
     return 0;
   }

src/test.cc

@@ -51,7 +51,7 @@ bool VirtualFileSystem::MakeDir(const string& path) {
   return true;  // success
 }
 
-string VirtualFileSystem::ReadFile(const string& path, string* err) {
+string VirtualFileSystem::ReadFile(const string& path, string* /* err */) {
   files_read_.push_back(path);
   FileMap::iterator i = files_.find(path);
   if (i != files_.end())