user32/tests: Use win_skip() where appropriate.

dlls/user32/tests/class.c

@@ -1115,7 +1115,7 @@ static void test_IME(void)
 
     if (!GetProcAddress(GetModuleHandleA("user32.dll"), "BroadcastSystemMessageExA"))
     {
-        skip("BroadcastSystemMessageExA not available, skipping IME class test\n");
+        win_skip("BroadcastSystemMessageExA not available, skipping IME class test\n");
         return;
     }
 

dlls/user32/tests/input.c

@@ -1361,7 +1361,7 @@ static void test_GetMouseMovePointsEx(void)
 
     /* Get a valid content for the input struct */
     if(!GetCursorPos(&point)) {
-        skip("GetCursorPos() failed with error %u\n", GetLastError());
+        win_skip("GetCursorPos() failed with error %u\n", GetLastError());
         return;
     }
     memset(&in, 0, sizeof(MOUSEMOVEPOINT));

dlls/user32/tests/winstation.c

@@ -932,7 +932,7 @@ START_TEST(winstation)
     GetProcessWindowStation();
     if (GetLastError() == ERROR_CALL_NOT_IMPLEMENTED)
     {
-        skip("WindowStation calls not supported on this platform\n");
+        win_skip("WindowStation calls not supported on this platform\n");
         return;
     }