Make sure stdio handles are in blocking mode

Standard I/O doesn't work well with non-blocking handles, so make sure any pipes are in blocking mode before launching child processes.

Fixes https://github.com/libsdl-org/SDL/issues/10998

src/process/windows/SDL_windowsprocess.c

@@ -73,6 +73,14 @@ static bool SetupRedirect(SDL_PropertiesID props, const char *property, HANDLE *
         WIN_SetError("DuplicateHandle()");
         return false;
     }
+
+    if (GetFileType(*result) == FILE_TYPE_PIPE) {
+        DWORD wait_mode = PIPE_WAIT;
+        if (!SetNamedPipeHandleState(*result, &wait_mode, NULL, NULL)) {
+            WIN_SetError("SetNamedPipeHandleState()");
+            return false;
+        }
+    }
     return true;
 }