update information about giflib bugs

Changes

@@ -940,6 +940,8 @@ Revision history for Perl extension Imager.
   to test/debug for 0.44.
 - image.h had no prototype for i_ft2_bbox_r() and it was being called
   from Imager.xs
+- giflib 4.1.3 still doesn't have all the bugs fixed, update the notes
+  in README and in the buggy_giflib.txt file that t105gif.t produces
 
 =================================================================
 

Makefile.PL

@@ -153,7 +153,11 @@ bugs.  Imager can crash or display other strange behaviour after
 reading or writing gif images.  Some of the gif tests can even fail
 since they stress some parts of the buggy code.
 
-libungif 4.1.2 and later is safe.
+libungif 4.1.2 and later is safe.  giflib 4.1.3 needs at least one
+patch to have all the bugs fixed, see README for details.
+
+Of course it's possible your operating system distributor has patched
+all of these problems and you have nothing to worry about.
 
 Do you want to remove gif support? [Y/n]
 EOFF

README

@@ -147,10 +147,17 @@ potential security problem.
 
 giflib/libungif has come a long way since the buggy versions around
 when Imager's gif support code was written.  Preferably you should get
-at least version 4.1.2.  If you have a recent Linux distribution you
+at least version 4.1.3.  If you have a recent Linux distribution you
 should be safe with whatever giflib it provides, but if you're
 building from source, please try to use the latest version.
 
+If you download giflib (as opposed to libungif) 4.1.3 from
+sourceforge, make sure you apply the patch referenced at:
+
+https://sourceforge.net/tracker/index.php?func=detail&aid=981255&group_id=102202&atid=631306
+
+libungif 4.1.3 does not need this patch.
+
 At the time of writing you will need to manually select to install the
 4.1.2-1 of cygwin's libungif package.
 

t/t105gif.t

@@ -209,8 +209,8 @@ ENDOFCODE
 	print FLAG <<EOS;
 This file is created by t105gif.t when test 14 fails.
 
-This failure usually indicates you\'re using the original version
-of giflib 4.1.0, which has a few bugs that Imager tickles.
+This failure usually indicates you\'re using the original versions
+of giflib 4.1.0 - 4.1.3, which have a few bugs that Imager tickles.
 
 You can apply the patch from:
 
@@ -219,6 +219,14 @@ http://www.develop-help.com/imager/giflib.patch
 or you can just install Imager as is, if you only need to write GIFs to 
 files or file descriptors (such as sockets).
 
+One hunk of this patch is rejected (correctly) with giflib 4.1.3,
+since one bug that the patch fixes is fixed in 4.1.3.
+
+If you don't feel comfortable with that apply the patch file that
+belongs to the following patch entry on sourceforge:
+
+https://sourceforge.net/tracker/index.php?func=detail&aid=981255&group_id=102202&atid=631306
+
 In previous versions of Imager only this test was careful about catching 
 the error, we now skip any tests that crashed or failed when the buggy 
 giflib was present.