Use libgif instead of libungif

Patch by Kevin McCarthy <signals@gentoo.org>

--- configure.in
+++ configure.in
@@ -286,20 +286,20 @@
 fi
 
 dnl
-dnl  Sprawdzamy libungif.so i <gif_lib.h>
+dnl  Sprawdzamy libgif.so i <gif_lib.h>
 dnl
   
-AC_ARG_WITH(libungif,
-	[  --without-libungif      Compile without GIF token support])
+AC_ARG_WITH(libgif,
+	[  --without-libgif      Compile without GIF token support])
 
-if test "x$with_libungif" != "xno"; then
-	AC_CHECK_LIB(ungif, DGifSlurp,
+if test "x$with_libgif" != "xno"; then
+	AC_CHECK_LIB(gif, DGifSlurp,
 	[ 
 		AC_CHECK_HEADERS(gif_lib.h,
 		[
-			AC_DEFINE(HAVE_LIBUNGIF, 1, [define if you have libungif])
-			LIBS="$LIBS -lungif"
-			have_libungif=yes
+			AC_DEFINE(HAVE_LIBUNGIF, 1, [define if you have libgif])
+			LIBS="$LIBS -lgif"
+			have_libgif=yes
 		])
 	])
 fi
@@ -478,10 +478,10 @@
 	echo " - zlib: disabled"
 fi
 
-if test "x$have_libungif" = "xyes"; then
-	echo " - libungif: enabled"
+if test "x$have_libgif" = "xyes"; then
+	echo " - libgif: enabled"
 else
-	echo " - libungif: disabled"
+	echo " - libgif: disabled"
 fi
 
 if test "x$have_libjpeg" = "xyes"; then