remove use of Mutex in favour of std::{,recursive_}mutex

This is a pretty straightforward first pass over removing a number of uses of
Mutex in favor of std::mutex or std::recursive_mutex. The problem is that there
are interfaces which take Mutex::Locker & to lock internal locks. This patch
cleans up most of the easy cases. The only non-trivial change is in
CommandObjectTarget.cpp where a Mutex::Locker was split into two.

llvm-svn: 269877
diff --git a/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h b/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h
index 27cdd3e..93f6be1 100644
--- a/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h
+++ b/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h
@@ -15,11 +15,12 @@
 #include <signal.h>
 
 // C++ Includes
+#include <mutex>
+
 // Other libraries and framework includes
 #include "lldb/lldb-types.h"
 #include "lldb/Host/FileSpec.h"
 #include "lldb/Host/HostThread.h"
-#include "lldb/Host/Mutex.h"
 
 namespace lldb_private
 {
@@ -223,7 +224,7 @@
 
     // current operation which must be executed on the privileged thread
     Operation *m_operation;
-    lldb_private::Mutex m_operation_mutex;
+    std::mutex m_operation_mutex;
 
     // semaphores notified when Operation is ready to be processed and when
     // the operation is complete.