Use safer xine_get_current_frame_s

xine_get_current_frame was deprecated back in 2019 because it is
"unsafe by design"[0].  The '_s' version was introduced in xine-lib
1.1.11, which was released in 2008, so there are no version checks.

[0]:
c1a154c1a8/

Signed-off-by: mio <stigma@disroot.org>

src/app/captureFrame.cpp

@@ -251,15 +251,16 @@ VideoWindow::captureFrame() const
    DEBUG_BLOCK
 
    int ratio, format, w, h;
-   if( !xine_get_current_frame( *engine(), &w, &h, &ratio, &format, NULL ) )
+   if (!xine_get_current_frame_s(*engine(), &w, &h, &ratio, &format, nullptr, nullptr))
       return TQImage();
 
-   uint8_t *yuv = new uint8_t[((w+8) * (h+1) * 2)];
+   int yuv_size = ((w + 8) * (h + 1)) * 2;
+   uint8_t *yuv = new uint8_t[yuv_size];
    if( yuv == 0 ) {
       Debug::error() << "Not enough memory to make screenframe!\n";
       return TQImage(); }
 
-   xine_get_current_frame( *engine(), &w, &h, &ratio, &format, yuv );
+   xine_get_current_frame_s(*engine(), &w, &h, &ratio, &format, yuv, &yuv_size);
 
    // convert to yv12 if necessary
    uint8_t *y = 0, *u = 0, *v = 0;