Add Perl language files

ftplugin/xs.vim

@@ -0,0 +1,14 @@
+" Vim filetype plugin file
+" Language:      XS (Perl extension interface language)
+" Maintainer:    vim-perl <vim-perl@googlegroups.com>
+" Homepage:      http://github.com/vim-perl/vim-perl
+" Bugs/requests: http://github.com/vim-perl/vim-perl/issues
+" Last Change:   {{LAST_CHANGE}}
+
+" 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