The PyCOND_TIMEDWAIT must use microseconds for the timeout argument

in order to have the same resolution as pthreads condition variables.
At the same time, it must be large enough to accept 31 bits of
milliseconds, which is the maximum timeout value in the windows API.
A PY_LONG_LONG of microseconds fullfills both requirements.
This closes issue #20737

Python/condvar.h

@@ -60,7 +60,7 @@
 #include <pthread.h>
 
 #define PyCOND_ADD_MICROSECONDS(tv, interval) \
-do { \
+do { /* TODO: add overflow and truncation checks */ \
     tv.tv_usec += (long) interval; \
     tv.tv_sec += tv.tv_usec / 1000000; \
     tv.tv_usec %= 1000000; \
@@ -89,7 +89,7 @@ do { \
 
 /* return 0 for success, 1 on timeout, -1 on error */
 Py_LOCAL_INLINE(int)
-PyCOND_TIMEDWAIT(PyCOND_T *cond, PyMUTEX_T *mut, long us)
+PyCOND_TIMEDWAIT(PyCOND_T *cond, PyMUTEX_T *mut, PY_LONG_LONG us)
 {
     int r;
     struct timespec ts;
@@ -270,9 +270,9 @@ PyCOND_WAIT(PyCOND_T *cv, PyMUTEX_T *cs)
 }
 
 Py_LOCAL_INLINE(int)
-PyCOND_TIMEDWAIT(PyCOND_T *cv, PyMUTEX_T *cs, long us)
+PyCOND_TIMEDWAIT(PyCOND_T *cv, PyMUTEX_T *cs, PY_LONG_LONG us)
 {
-    return _PyCOND_WAIT_MS(cv, cs, us/1000);
+    return _PyCOND_WAIT_MS(cv, cs, (DWORD)(us/1000));
 }
 
 Py_LOCAL_INLINE(int)
@@ -363,9 +363,9 @@ PyCOND_WAIT(PyCOND_T *cv, PyMUTEX_T *cs)
  * 2 to indicate that we don't know.
  */
 Py_LOCAL_INLINE(int)
-PyCOND_TIMEDWAIT(PyCOND_T *cv, PyMUTEX_T *cs, long us)
+PyCOND_TIMEDWAIT(PyCOND_T *cv, PyMUTEX_T *cs, PY_LONG_LONG us)
 {
-    return SleepConditionVariableSRW(cv, cs, us/1000, 0) ? 2 : -1;
+    return SleepConditionVariableSRW(cv, cs, (DWORD)(us/1000), 0) ? 2 : -1;
 }
 
 Py_LOCAL_INLINE(int)

Python/thread_nt.h

@@ -77,7 +77,7 @@ EnterNonRecursiveMutex(PNRMUTEX mutex, DWORD milliseconds)
         /* wait at least until the target */
         DWORD now, target = GetTickCount() + milliseconds;
         while (mutex->locked) {
-            if (PyCOND_TIMEDWAIT(&mutex->cv, &mutex->cs, milliseconds*1000) < 0) {
+            if (PyCOND_TIMEDWAIT(&mutex->cv, &mutex->cs, (PY_LONG_LONG)milliseconds*1000) < 0) {
                 result = WAIT_FAILED;
                 break;
             }