Update runtime files.

runtime/doc/syntax.txt

@@ -1,4 +1,4 @@
-*syntax.txt*	For Vim version 7.4.  Last change: 2014 Nov 19
+*syntax.txt*	For Vim version 7.4.  Last change: 2015 Jan 07
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -1128,6 +1128,14 @@ to standard by placing this in your vimrc file: >
 	:let enforce_freedesktop_standard = 1
 
 
+DIFF							*diff.vim*
+
+The diff highlighting normally finds translated headers.  This can be slow if
+there are very long lines in the file.  To disable translations: >
+
+	:let diff_translations = 0
+
+
 DIRCOLORS			       *dircolors.vim* *ft-dircolors-syntax*
 
 The dircolors utility highlighting definition has one option.  It exists to