shill: Remove unnecessary extern "C" declaration around glib-unix.h

In glib 2.30, there is a missing extern "C" declaration in glib-unix.h.
An extern "C" declaration was added around the inclusion of glib-unix.h
in shill to address that issue. This is no longer needed as the
dev-libs/glib-2.30.0-r2 package has a patch that fixes the issue.

BUG=none
TEST=Build and run unit tests.

Change-Id: I69927d5e5416966c8feee8f17587ce9a11ccf873
Reviewed-on: https://gerrit.chromium.org/gerrit/20669
Tested-by: Ben Chan <benchan@chromium.org>
Commit-Ready: Ben Chan <benchan@chromium.org>
Reviewed-by: Darin Petkov <petkov@chromium.org>
diff --git a/shill_main.cc b/shill_main.cc
index 8331ef6..f4e06dc 100644
--- a/shill_main.cc
+++ b/shill_main.cc
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <glib-unix.h>
 #include <time.h>
 #include <unistd.h>
 
@@ -16,10 +17,6 @@
 #include <base/string_split.h>
 #include <chromeos/syslog_logging.h>
 
-extern "C" {
-#include <glib-unix.h>
-}
-
 #include "shill/dbus_control.h"
 #include "shill/shill_config.h"
 #include "shill/shill_daemon.h"