Don't require semantic/fw

* lisp/progmodes/xref.el (xref-collect-matches): Don't require
semantic/fw, we haven't been using semantic-find-file-noselect
here for a while.

lisp/progmodes/xref.el

@@ -1164,7 +1164,6 @@ and when."
 FILES is a string with glob patterns separated by spaces.
 IGNORES is a list of glob patterns."
   ;; DIR can also be a regular file for now; let's not advertise that.
-  (require 'semantic/fw)
   (grep-compute-defaults)
   (defvar grep-find-template)
   (defvar grep-highlight-matches)