Add syntax files from upstream vim repository

syntax/ctrlh.vim

@@ -0,0 +1,27 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'vim') == -1
+  
+" Vim syntax file
+" Language:	CTRL-H (e.g., ASCII manpages)
+" Maintainer:	Bram Moolenaar <Bram@vim.org>
+" Last Change:	2005 Jun 20
+
+" Existing syntax is kept, this file can be used as an addition
+
+" Recognize underlined text: _^Hx
+syntax match CtrlHUnderline /_\b./  contains=CtrlHHide
+
+" Recognize bold text: x^Hx
+syntax match CtrlHBold /\(.\)\b\1/  contains=CtrlHHide
+
+" Hide the CTRL-H (backspace)
+syntax match CtrlHHide /.\b/  contained
+
+" Define the default highlighting.
+" Only used when an item doesn't have highlighting yet
+hi def link CtrlHHide Ignore
+hi def CtrlHUnderline term=underline cterm=underline gui=underline
+hi def CtrlHBold term=bold cterm=bold gui=bold
+
+" vim: ts=8
+
+endif