added two xs.vim files from the vim share directory

Changes

@@ -7,6 +7,8 @@ perl5:
 
 Fix overzealous matching of /^package/ inside Pod (Hinrik)
 
+Added xs.vim.
+
 [FIXES]
 Minor tweak to p6RxCharClass.  Thanks, Arne Skjærholt.
 

ftplugin/xs.vim

@@ -0,0 +1,12 @@
+" Vim filetype plugin file
+" Language:	XS (Perl extension interface language)
+" Maintainer:	Bram Moolenaar <Bram@vim.org>
+" Last Change:	2001 Sep 18
+
+" Only do this when not done yet for this buffer
+if exists("b:did_ftplugin")
+  finish
+endif
+
+" Just use the C plugin for now.
+runtime! ftplugin/c.vim ftplugin/c_*.vim ftplugin/c/*.vim

syntax/xs.vim

@@ -0,0 +1,54 @@
+" Vim syntax file
+" Language:	XS (Perl extension interface language)
+" Maintainer:	Michael W. Dodge <sarge@pobox.com>
+" Last Change:	2001 May 09
+
+" For version 5.x: Clear all syntax items
+" For version 6.x: Quit when a syntax file was already loaded
+if version < 600
+  syntax clear
+elseif exists("b:current_syntax")
+  finish
+endif
+
+" Read the C syntax to start with
+if version < 600
+  source <sfile>:p:h/c.vim
+else
+  runtime! syntax/c.vim
+endif
+
+" XS extentions
+" TODO: Figure out how to look for trailing '='.
+syn keyword xsKeyword	MODULE PACKAGE PREFIX
+syn keyword xsKeyword	OUTPUT: CODE: INIT: PREINIT: INPUT:
+syn keyword xsKeyword	PPCODE: REQUIRE: CLEANUP: BOOT:
+syn keyword xsKeyword	VERSIONCHECK: PROTOTYPES: PROTOTYPE:
+syn keyword xsKeyword	ALIAS: INCLUDE: CASE:
+" TODO: Figure out how to look for trailing '('.
+syn keyword xsMacro	SV EXTEND PUSHs
+syn keyword xsVariable	RETVAL NO_INIT
+"syn match xsCast	"\<\(const\|static\|dynamic\|reinterpret\)_cast\s*<"me=e-1
+"syn match xsCast	"\<\(const\|static\|dynamic\|reinterpret\)_cast\s*$"
+
+" Define the default highlighting.
+" For version 5.7 and earlier: only when not done already
+" For version 5.8 and later: only when an item doesn't have highlighting yet
+if version >= 508 || !exists("did_xs_syntax_inits")
+  if version < 508
+    let did_xs_syntax_inits = 1
+    command -nargs=+ HiLink hi link <args>
+  else
+    command -nargs=+ HiLink hi def link <args>
+  endif
+
+  HiLink xsKeyword	Keyword
+  HiLink xsMacro	Macro
+  HiLink xsVariable	Identifier
+
+  delcommand HiLink
+endif
+
+let b:current_syntax = "xs"
+
+" vim: ts=8