compat/w32pthreads: use the CONDITION_VARIABLE typedef if available

This silences warnings about passing arguments from incompatible pointer type
when targeting Windows Vista or newer.
Tested-by: Matt Oliver <protogonoi@gmail.com>
Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: James Almer <jamrial@gmail.com>

compat/w32pthreads.h

@@ -55,12 +55,15 @@ typedef struct pthread_t {
  * not mutexes */
 typedef CRITICAL_SECTION pthread_mutex_t;
 
-/* This is the CONDITIONAL_VARIABLE typedef for using Window's native
- * conditional variables on kernels 6.0+.
- * MinGW does not currently have this typedef. */
+/* This is the CONDITION_VARIABLE typedef for using Windows' native
+ * conditional variables on kernels 6.0+. */
+#if HAVE_CONDITION_VARIABLE_PTR
+typedef CONDITION_VARIABLE pthread_cond_t;
+#else
 typedef struct pthread_cond_t {
-    void *ptr;
+    void *Ptr;
 } pthread_cond_t;
+#endif
 
 /* function pointers to conditional variable API on windows 6.0+ kernels */
 #if _WIN32_WINNT < 0x0600
@@ -159,7 +162,7 @@ static av_unused int pthread_cond_init(pthread_cond_t *cond, const void *unused_
     win32_cond = av_mallocz(sizeof(win32_cond_t));
     if (!win32_cond)
         return ENOMEM;
-    cond->ptr = win32_cond;
+    cond->Ptr = win32_cond;
     win32_cond->semaphore = CreateSemaphore(NULL, 0, 0x7fffffff, NULL);
     if (!win32_cond->semaphore)
         return ENOMEM;
@@ -174,7 +177,7 @@ static av_unused int pthread_cond_init(pthread_cond_t *cond, const void *unused_
 
 static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
 {
-    win32_cond_t *win32_cond = cond->ptr;
+    win32_cond_t *win32_cond = cond->Ptr;
     /* native condition variables do not destroy */
     if (cond_init)
         return;
@@ -185,12 +188,12 @@ static av_unused void pthread_cond_destroy(pthread_cond_t *cond)
     pthread_mutex_destroy(&win32_cond->mtx_waiter_count);
     pthread_mutex_destroy(&win32_cond->mtx_broadcast);
     av_freep(&win32_cond);
-    cond->ptr = NULL;
+    cond->Ptr = NULL;
 }
 
 static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
 {
-    win32_cond_t *win32_cond = cond->ptr;
+    win32_cond_t *win32_cond = cond->Ptr;
     int have_waiter;
 
     if (cond_broadcast) {
@@ -221,7 +224,7 @@ static av_unused void pthread_cond_broadcast(pthread_cond_t *cond)
 
 static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 {
-    win32_cond_t *win32_cond = cond->ptr;
+    win32_cond_t *win32_cond = cond->Ptr;
     int last_waiter;
     if (cond_wait) {
         cond_wait(cond, mutex, INFINITE);
@@ -253,7 +256,7 @@ static av_unused int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mu
 
 static av_unused void pthread_cond_signal(pthread_cond_t *cond)
 {
-    win32_cond_t *win32_cond = cond->ptr;
+    win32_cond_t *win32_cond = cond->Ptr;
     int have_waiter;
     if (cond_signal) {
         cond_signal(cond);

configure

@@ -1767,6 +1767,7 @@ TOOLCHAIN_FEATURES="
 "
 
 TYPES_LIST="
+    CONDITION_VARIABLE_Ptr
     socklen_t
     struct_addrinfo
     struct_group_source_req
@@ -4719,6 +4720,7 @@ check_func_headers windows.h PeekNamedPipe
 check_func_headers windows.h SetConsoleTextAttribute
 check_func_headers windows.h Sleep
 check_func_headers windows.h VirtualAlloc
+check_struct windows.h "CONDITION_VARIABLE" Ptr
 check_func_headers glob.h glob
 enabled xlib &&
     check_func_headers "X11/Xlib.h X11/extensions/Xvlib.h" XvGetPortAttribute -lXv -lX11 -lXext