fix build on windows port

port/port_posix.h

@@ -238,11 +238,12 @@ int64_t GetProcessID();
 bool GenerateRfcUuid(std::string* output);
 
 // Is called in the context of background threads.
-// Blocks the termination handlers of pthread from running in the context of the calling thread.
-// We block various termination signals (other than SIGKILL which we both cannot and do not want to block)
-// in the background threads where we do not wish our environment destructors to be called.
-// If the environment destructor is called inside a background thread we will encounter undefined behaviour,
-// such as a thread waiting on itself.
+// Blocks the termination handlers of pthread from running in the context of the
+// calling thread. We block various termination signals (other than SIGKILL
+// which we both cannot and do not want to block) in the background threads
+// where we do not wish our environment destructors to be called. If the
+// environment destructor is called inside a background thread we will encounter
+// undefined behaviour, such as a thread waiting on itself.
 extern void BlockTerminationSignals();
 
 } // namespace port

port/win/port_win.cc

@@ -297,6 +297,8 @@ bool GenerateRfcUuid(std::string* output) {
   return true;
 }
 
+void BlockTerminationSignals() {}
+
 }  // namespace port
 }  // namespace ROCKSDB_NAMESPACE
 

port/win/port_win.h

@@ -362,7 +362,7 @@ int64_t GetProcessID();
 // true on success or false on failure.
 bool GenerateRfcUuid(std::string* output);
 
-void BlockTerminationSignals(){}
+extern void BlockTerminationSignals();
 
 }  // namespace port