Add syntax files from upstream vim repository

syntax/groff.vim

@@ -0,0 +1,14 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'vim') == -1
+  
+" VIM syntax file
+" Language:	groff
+" Maintainer:	Alejandro L<>pez-Valencia <dradul@yahoo.com>
+" URL:		http://dradul.tripod.com/vim
+" Last Change:	2003-05-08-12:41:13 GMT-5.
+
+" This uses the nroff.vim syntax file.
+let b:main_syntax = "nroff"
+let b:nroff_is_groff = 1
+runtime! syntax/nroff.vim
+
+endif