Fix some C++11 requirements.

src/V3Options.cpp

@@ -1369,10 +1369,10 @@ void V3Options::parseOptsFile(FileLine* fl, const string& filename, bool rel) {
 
     // Convert to argv style arg list and parse them
     std::vector<char*> argv; argv.reserve(args.size()+1);
-    for (const string &arg : args) {
-        argv.push_back(const_cast<char*>(arg.c_str()));
+    for (std::vector<std::string>::const_iterator it = args.begin(); it != args.end(); ++it) {
+        argv.push_back(const_cast<char*>(it->c_str()));
     }
-    argv.push_back(nullptr); // argv is NULL-terminated
+    argv.push_back(NULL); // argv is NULL-terminated
     parseOptsList(fl, optdir, static_cast<int>(argv.size()-1), argv.data());
 }
 

src/V3Os.cpp

@@ -161,7 +161,7 @@ string V3Os::filenameSubstitute(const string& filename) {
             }
             string envvar = filename.substr(pos+1, endpos-pos);
             string envvalue;
-            if (!envvar.empty()) envvalue = getenvStr(envvar, {});
+            if (!envvar.empty()) envvalue = getenvStr(envvar, "");
             if (!envvalue.empty()) {
                 out += envvalue;
                 if (brackets==NONE) pos = endpos;