thread/Cond: add wait() overload which takes a unique_lock<>

Just like std::condition_variable, which however has no way to specify
the std::mutex directly.

src/thread/PosixCond.hxx

@@ -33,6 +33,7 @@
 #include "PosixMutex.hxx"
 
 #include <chrono>
+#include <mutex>
 
 #include <sys/time.h>
 
@@ -74,6 +75,11 @@ public:
 		pthread_cond_wait(&cond, &mutex.mutex);
 	}
 
+	template<typename M>
+	void wait(std::unique_lock<M> &lock) noexcept {
+		wait(*lock.mutex());
+	}
+
 private:
 	bool wait_for(PosixMutex &mutex, uint_least32_t timeout_us) noexcept {
 		struct timeval now;
@@ -102,6 +108,12 @@ public:
 
 		return wait_for(mutex, timeout_us);
 	}
+
+	template<typename M>
+	bool wait_for(std::unique_lock<M> &lock,
+		      std::chrono::steady_clock::duration timeout) noexcept {
+		return wait_for(*lock.mutex(), timeout);
+	}
 };
 
 #endif

src/thread/WindowsCond.hxx

@@ -33,6 +33,7 @@
 #include "CriticalSection.hxx"
 
 #include <chrono>
+#include <mutex>
 
 /**
  * Wrapper for a CONDITION_VARIABLE, backend for the Cond class.
@@ -69,9 +70,20 @@ public:
 		return wait_for(mutex, timeout_ms);
 	}
 
+	template<typename M>
+	bool wait_for(std::unique_lock<M> &lock,
+		      std::chrono::steady_clock::duration timeout) noexcept {
+		return wait_for(*lock.mutex(), timeout);
+	}
+
 	void wait(CriticalSection &mutex) noexcept {
 		wait_for(mutex, INFINITE);
 	}
+
+	template<typename M>
+	void wait(std::unique_lock<M> &lock) noexcept {
+		wait(*lock.mutex());
+	}
 };
 
 #endif