HHVM Debugger: initialize server variables for dummy request thread

Summary:
When invoked from the command line, certain server variables (like request start time) are set in $_SERVER, but this is not happening for the dummy request thread in the new debugger. The old XDebug debugger got this for free, because the dummy was started as a separate CLI invocation of HHVM, which went through the CLI initialization path.

This is causing things like request_time() to fail when used in the console REPL.

Reviewed By: rightparen

Differential Revision: D6962253

fbshipit-source-id: 5524a1109da609b36b5e0a8feee73a949ec7fbd0

hphp/runtime/ext/vsdebug/session.cpp

@@ -146,6 +146,9 @@ void DebuggerSession::runDummy() {
  );

  hphp_session_init();
  init_command_line_globals(0, nullptr, environ, 0,
                            RuntimeOption::ServerVariables,
                            RuntimeOption::EnvVariables);
  SCOPE_EXIT {
    if (m_dummyRequestInfo->m_flags.hookAttached) {
      DebuggerHook::detach();