Expose underlying clock in CThreadInterrupt

Overloading sleep_for is not needed, as

* seconds and minutes can be converted to milliseconds by the compiler,
  not needing a duration_cast
* std::condition_variable::wait_for will convert milliseconds to the
  duration type of the underlying clock

So simply expose the clock.

ci/test/06_script_b.sh

@@ -47,6 +47,7 @@ if [ "${RUN_TIDY}" = "true" ]; then
           " src/rpc/fees.cpp"\
           " src/rpc/signmessage.cpp"\
           " src/test/fuzz/txorphan.cpp"\
+          " src/threadinterrupt.cpp"\
           " src/util/bip32.cpp"\
           " src/util/bytevectorhash.cpp"\
           " src/util/error.cpp"\

src/threadinterrupt.cpp

@@ -28,18 +28,8 @@ void CThreadInterrupt::operator()()
     cond.notify_all();
 }
 
-bool CThreadInterrupt::sleep_for(std::chrono::milliseconds rel_time)
+bool CThreadInterrupt::sleep_for(Clock::duration rel_time)
 {
     WAIT_LOCK(mut, lock);
     return !cond.wait_for(lock, rel_time, [this]() { return flag.load(std::memory_order_acquire); });
 }
-
-bool CThreadInterrupt::sleep_for(std::chrono::seconds rel_time)
-{
-    return sleep_for(std::chrono::duration_cast<std::chrono::milliseconds>(rel_time));
-}
-
-bool CThreadInterrupt::sleep_for(std::chrono::minutes rel_time)
-{
-    return sleep_for(std::chrono::duration_cast<std::chrono::milliseconds>(rel_time));
-}

src/threadinterrupt.h

@@ -19,13 +19,12 @@
 class CThreadInterrupt
 {
 public:
+    using Clock = std::chrono::steady_clock;
     CThreadInterrupt();
     explicit operator bool() const;
     void operator()() EXCLUSIVE_LOCKS_REQUIRED(!mut);
     void reset();
-    bool sleep_for(std::chrono::milliseconds rel_time) EXCLUSIVE_LOCKS_REQUIRED(!mut);
-    bool sleep_for(std::chrono::seconds rel_time) EXCLUSIVE_LOCKS_REQUIRED(!mut);
-    bool sleep_for(std::chrono::minutes rel_time) EXCLUSIVE_LOCKS_REQUIRED(!mut);
+    bool sleep_for(Clock::duration rel_time) EXCLUSIVE_LOCKS_REQUIRED(!mut);
 
 private:
     std::condition_variable cond;