libCom: cross mingw imports posix time.h by default

at least mingw 4.9.1 for Debian 8 i386 host.

src/ioc/db/test/dbStressLock.c

@@ -40,7 +40,7 @@
 
 #include "xRecord.h"
 
-#if defined(CLOCK_MONOTONIC)
+#if defined(CLOCK_MONOTONIC) && !defined(_WIN32)
 # define TIME_STATS
 #endif
 
@@ -175,8 +175,8 @@ void worker(void *raw)
         double sel = getRand();
 #ifdef TIME_STATS
         struct timespec after;
-#endif
         double duration;
+#endif
 
         int act;
         if(sel<0.33) {

src/libCom/osi/osiClockTime.c

@@ -39,7 +39,7 @@ static struct {
 static epicsThreadOnceId onceId = EPICS_THREAD_ONCE_INIT;
 
 
-#ifdef CLOCK_REALTIME
+#if defined(CLOCK_REALTIME) && !defined(_WIN32)
 /* This code is not used on systems without Posix CLOCK_REALTIME such
  * as Darwin, but the only way to detect that is from the OS headers,
  * so the Makefile can't exclude building this file on those systems.