Update some usleep() to std::chrono

Ideally this fixes some issues on windows where usleep
appears to misfunction, but if not there will be another
commit for lower resolution systems.

src/Misc/MiddleWare.cpp

@@ -48,6 +48,8 @@
 #include <string>
 #include <future>
 #include <atomic>
+#include <chrono>
+#include <thread>
 #include <list>
 
 #define errx(...) {}
@@ -1554,14 +1556,15 @@ MiddleWareImpl::~MiddleWareImpl(void)
 
 void MiddleWareImpl::doReadOnlyOp(std::function<void()> read_only_fn)
 {
+    using namespace std::chrono;
     assert(uToB);
     uToB->write("/freeze_state","");
 
     std::list<const char *> fico;
     int tries = 0;
     while(tries++ < 10000) {
         if(!bToU->hasNext()) {
-            usleep(500);
+            std::this_thread::sleep_for(microseconds(500));
             continue;
         }
         const char *msg = bToU->read();
@@ -1667,14 +1670,15 @@ void MiddleWareImpl::doReadOnlyOpPlugin(std::function<void()> read_only_fn)
 
 bool MiddleWareImpl::doReadOnlyOpNormal(std::function<void()> read_only_fn, bool canfail)
 {
+    using namespace std::chrono;
     assert(uToB);
     uToB->write("/freeze_state","");
 
     std::list<const char *> fico;
     int tries = 0;
     while(tries++ < 2000) {
         if(!bToU->hasNext()) {
-            usleep(500);
+            std::this_thread::sleep_for(microseconds(500));
             continue;
         }
         const char *msg = bToU->read();

src/Nio/NulEngine.cpp

@@ -14,7 +14,8 @@
 #include "NulEngine.h"
 #include "../globals.h"
 
-#include <unistd.h>
+#include <thread>
+#include <chrono>
 #include <iostream>
 using namespace std;
 
@@ -35,6 +36,7 @@ void *NulEngine::_AudioThread(void *arg)
 
 void *NulEngine::AudioThread()
 {
+    using namespace std::chrono;
     while(pThread) {
         getNext();
 
@@ -50,7 +52,7 @@ void *NulEngine::AudioThread()
                         + (playing_until.tv_sec - now.tv_sec) * 1000000;
             if(remaining > 10000) //Don't sleep() less than 10ms.
                 //This will add latency...
-                usleep(remaining - 10000);
+                std::this_thread::sleep_for(std::chrono::microseconds(remaining  - 10000));
             if(remaining < 0)
                 cerr << "WARNING - too late" << endl;
         }