Replace RW lock with mutex, shared_mutex

Test: built, flashed, booted
      system/netd/tests/runtests.sh passes
Change-Id: I42b52d815b6ba0ba6f93dc27e83a900d2abec715
diff --git a/server/NetdConstants.h b/server/NetdConstants.h
index 4f7d923..8db9ba3 100644
--- a/server/NetdConstants.h
+++ b/server/NetdConstants.h
@@ -17,6 +17,7 @@
 #ifndef _NETD_CONSTANTS_H
 #define _NETD_CONSTANTS_H
 
+#include <mutex>
 #include <string>
 #include <list>
 #include <ifaddrs.h>
@@ -27,8 +28,6 @@
 
 #include <private/android_filesystem_config.h>
 
-#include "utils/RWLock.h"
-
 const int PROTECT_MARK = 0x1;
 const int MAX_SYSTEM_UID = AID_APP - 1;
 
@@ -93,7 +92,7 @@
  * CommandListener has only one user (NetworkManagementService), which is connected through a
  * FrameworkListener that passes in commands one at a time.
  */
-extern android::RWLock gBigNetdLock;
+extern std::mutex gBigNetdLock;
 
 }  // namespace net
 }  // namespace android