compext/Png.c: fix shadowing

Png.c: In function ‘PngWriteData’:
Png.c:603:38: warning: declaration of ‘png_ptr’ shadows a global declaration [-Wshadow]
  603 | static void PngWriteData(png_structp png_ptr, png_bytep data, png_size_t length)
      |                          ~~~~~~~~~~~~^~~~~~~
Png.c:77:13: note: shadowed declaration is here
   77 | png_structp png_ptr;
      |             ^~~~~~~
Png.c: In function ‘PngFlushData’:
Png.c:610:38: warning: declaration of ‘png_ptr’ shadows a global declaration [-Wshadow]
  610 | static void PngFlushData(png_structp png_ptr)
      |                          ~~~~~~~~~~~~^~~~~~~
Png.c:77:13: note: shadowed declaration is here
   77 | png_structp png_ptr;
      |             ^~~~~~~

1 files changed, 3 insertions, 3 deletions

diff --git a/nx-X11/programs/Xserver/hw/nxagent/compext/Png.c b/nx-X11/programs/Xserver/hw/nxagent/compext/Png.c
index 00f6769f8..48acb6e88 100644
--- a/nx-X11/programs/Xserver/hw/nxagent/compext/Png.c
+++ b/nx-X11/programs/Xserver/hw/nxagent/compext/Png.c
@@ -602,14 +602,14 @@ char *PngCompressData(XImage *image, int *compressed_size)
   }
 }
 
-static void PngWriteData(png_structp png_ptr, png_bytep data, png_size_t length)
+static void PngWriteData(png_structp _png_ptr, png_bytep data, png_size_t length)
 {
-  memcpy(((char *) png_get_io_ptr(png_ptr) + pngDataLen), data, length);
+  memcpy(((char *) png_get_io_ptr(_png_ptr) + pngDataLen), data, length);
 
   pngDataLen += length;
 }
 
-static void PngFlushData(png_structp png_ptr)
+static void PngFlushData(png_structp _png_ptr)
 {
 }