various build system improvements

tools/pngprepare.c

@@ -361,7 +361,7 @@ void process_file(int mode, char *outputfilename)
     // 4KB = 2x 256 char = 2KB charsets
     for(charsets = 0 ; charsets<2 ; charsets++) {
       if (bytes>=4096) break;
-      fprintf(stderr,"yheight=%d\n",height);
+      fprintf(stdout,"yheight=%d\n",height);
       for (y=0; y<height; y++) {
 	png_byte* row = row_pointers[y];
 	int byte=0;