uhd: Replace Boost mutexes and locks with standard options

This is a very mechanical task that could almost have been done with
sed. Boost versions of mutexes and locks were removed, and replaced with
std:: versions. The replacement tables are as follows:

== Mutexes ==
- boost::mutex -> std::mutex
- boost::recursive_mutex -> std::recursive_mutex

Mutexes behave identically between Boost and std:: and have the same
API.

== Locks ==
C++11 has only two types of lock that we use/need in UHD:
- std::lock_guard: Identical to boost::lock_guard
- std::unique_lock: Identical to boost::unique_lock

Boost also has boost::mutex::scoped_lock, which is a typedef for
boost::unique_lock<>. However, we often have used scoped_lock where we
meant to use lock_guard<>. The name is a bit misleading, "scoped lock"
sounding a bit like an RAII mechanism. Therefore, some previous
boost::mutex::scoped_lock are now std::lock_guard<>.

std::unique_lock is required when doing more than RAII locking (i.e.,
unlocking, relocking, usage with condition variables, etc.).

== Condition Variables ==
Condition variables were out of the scope of this lock/mutex change, but
in UHD, we inconsistently use boost::condition vs.
boost::condition_variable. The former is a templated version of the
latter, and thus works fine with std::mutex'es. Therefore, some
boost::condition_variable where changed to boost::condition.

All locks and mutexes use `#include <mutex>`. The corresponding Boost
includes were removed. In some cases, this exposed issues with implicit
Boost includes elsewhere. The missing explicit includes were added.

1 files changed, 3 insertions, 3 deletions

diff --git a/host/lib/transport/libusb1_control.cpp b/host/lib/transport/libusb1_control.cpp
index e6339e17f..5d49e3931 100644
--- a/host/lib/transport/libusb1_control.cpp
+++ b/host/lib/transport/libusb1_control.cpp
@@ -7,7 +7,7 @@
 
 #include "libusb1_base.hpp"
 #include <uhd/transport/usb_control.hpp>
-#include <boost/thread/mutex.hpp>
+#include <mutex>
 
 using namespace uhd::transport;
 
@@ -38,7 +38,7 @@ public:
         uint16_t length,
         uint32_t libusb_timeout = 0) override
     {
-        boost::mutex::scoped_lock lock(_mutex);
+        std::lock_guard<std::mutex> lock(_mutex);
         return libusb_control_transfer(_handle->get(),
             request_type,
             request,
@@ -51,7 +51,7 @@ public:
 
 private:
     libusb::device_handle::sptr _handle;
-    boost::mutex _mutex;
+    std::mutex _mutex;
 };
 
 libusb_control_impl::~libusb_control_impl(void)