This patch addresses a number of compiler warnings about dubious type
conversions.

Most importantly, it fixes some buffer overflow checks using
invalid constructs like this:

  int filesize = get_file_size();
  if (filesize + 256 < filesize) ...

Integer overflow operation is undefined for signed values, so this
check can legitimately be optimized out, hence losing the buffer
overflow check.

--- xv-3.10a/xvbutt.c.clean	2009-08-21 10:01:04.000000000 +0100
+++ xv-3.10a/xvbutt.c	2009-08-21 13:06:48.000000000 +0100
@@ -843,7 +843,7 @@
      int           x,y;
      unsigned int  w,h;
      const char   *title;
-     const char  * const *list;
+     const char  **list;
      int           nlist;
      unsigned long fg,bg,hi,lo;
 {
--- xv-3.10a/xvgif.c.clean	2009-08-21 10:26:28.000000000 +0100
+++ xv-3.10a/xvgif.c	2009-08-21 10:46:25.000000000 +0100
@@ -100,7 +100,7 @@
 static int   gifError    PARM((PICINFO *, const char *));
 static void  gifWarning  PARM((const char *));
 
-static int         filesize;
+static long int    filesize;
 static const char *bname;
 static byte       *dataptr;
 
@@ -140,7 +140,7 @@
   filesize = ftell(fp);
   fseek(fp, 0L, 0);
 
-  if (filesize + 256 < filesize)
+  if (filesize > (2147483647L - 256))
     return( gifError(pinfo, "GIF file size is too large") );
 
   /* the +256's are so we can read truncated GIF files without fear of
@@ -769,7 +769,7 @@
   pinfo->normw = pinfo->w;   pinfo->normh = pinfo->h;
 
   sprintf(pinfo->fullInfo,
-	  "GIF%s, %d bit%s per pixel, %sinterlaced.  (%d bytes)",
+	  "GIF%s, %d bit%s per pixel, %sinterlaced.  (%ld bytes)",
  	  (gif89) ? "89" : "87", BitsPerPixel,
 	  (BitsPerPixel==1) ? "" : "s",
  	  Interlace ? "" : "non-", filesize);
--- xv-3.10a/xv.h.clean	2009-08-21 10:01:05.000000000 +0100
+++ xv-3.10a/xv.h	2009-08-21 13:17:17.000000000 +0100
@@ -1587,7 +1595,7 @@
 
 
 void   MBCreate            PARM((MBUTT *, Window, int, int, u_int, u_int,
-				 const char *, const char * const *, int,
+				 const char *, const char **, int,
 				 u_long, u_long, u_long, u_long));
 
 void   MBRedraw            PARM((MBUTT *));
--- xv-3.10a/xvsunras.c.clean	2009-08-21 10:01:04.000000000 +0100
+++ xv-3.10a/xvsunras.c	2009-08-21 13:01:07.000000000 +0100
@@ -54,7 +54,7 @@
      PICINFO *pinfo;
 {
   FILE	*fp;
-  int	 linesize,lsize,csize,isize,i,w,h,d,npixels,nbytes;
+  unsigned int	 linesize,lsize,csize,isize,i,w,h,d,npixels,nbytes;
   byte	 *image, *line;
   struct rasterfile sunheader;
   const char *bname;
--- xv-3.10a/xvwbmp.c.clean	2009-08-21 12:57:13.000000000 +0100
+++ xv-3.10a/xvwbmp.c	2009-08-21 12:58:38.000000000 +0100
@@ -75,7 +75,7 @@
     int im_type;	/* image type (only type 0 supported) */
     uint8 fix_header;	/* fixed header field */
     int width, height;
-    int npixels, raw_size, aux;
+    unsigned int npixels, raw_size, aux;
     uint8 * raw;
 
     st_fname = fname;