gnu: vim: Use upstream fix for CVE-2017-5953.

* gnu/packages/patches/vim-CVE-2017-5953.patch: Adjust to match upstream changes.

gnu/packages/patches/vim-CVE-2017-5953.patch

@@ -3,20 +3,28 @@ Fix CVE-2017-5953:
 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-5953
 https://groups.google.com/forum/#!topic/vim_dev/t-3RSdEnrHY
 
-Patch adapted from upstream commit, correcting the transcription error
-in the bounds check:
+This change is adapted from the upstream source repository:
 
-https://github.com/vim/vim/commit/399c297aa93afe2c0a39e2a1b3f972aebba44c9d
+https://github.com/vim/vim/commit/6d3c8586fc81b022e9f06c611b9926108fb878c7
 
 diff --git a/src/spellfile.c b/src/spellfile.c
-index c7d87c6..8b1a3a6 100644
+index c7d87c6..00ef019 100644
 --- a/src/spellfile.c
 +++ b/src/spellfile.c
+@@ -1585,7 +1585,7 @@ spell_read_tree(
+     int		prefixtree,	/* TRUE for the prefix tree */
+     int		prefixcnt)	/* when "prefixtree" is TRUE: prefix count */
+ {
+-    int		len;
++    long	len;
+     int		idx;
+     char_u	*bp;
+     idx_T	*ip;
 @@ -1595,6 +1595,9 @@ spell_read_tree(
      len = get4c(fd);
      if (len < 0)
  	return SP_TRUNCERROR;
-+    if (len >= 0x3fffffff)
++    if (len >= LONG_MAX / (long)sizeof(int))
 +	/* Invalid length, multiply with sizeof(int) would overflow. */
 +	return SP_FORMERROR;
      if (len > 0)