Use save-excursion in xref-location-marker more

* lisp/progmodes/elisp-mode.el (xref-location-marker): Use
save-excursion, in order not to alter the value of point if the
buffer is currently open in the background (problem reported by
Robert Weiner).

* lisp/progmodes/etags.el (xref-location-marker): Same.

lisp/progmodes/elisp-mode.el

@@ -826,8 +826,9 @@ non-nil result supercedes the xrefs produced by
   (pcase-let (((cl-struct xref-elisp-location symbol type file) l))
     (let ((buffer-point (find-function-search-for-symbol symbol type file)))
       (with-current-buffer (car buffer-point)
+        (save-excursion
           (goto-char (or (cdr buffer-point) (point-min)))
-        (point-marker)))))
+          (point-marker))))))
 
 (cl-defmethod xref-location-group ((l xref-elisp-location))
   (xref-elisp-location-file l))

lisp/progmodes/etags.el

@@ -2146,8 +2146,9 @@ for \\[find-tag] (which see)."
   (with-slots (tag-info file) l
     (let ((buffer (find-file-noselect file)))
       (with-current-buffer buffer
+        (save-excursion
           (etags-goto-tag-location tag-info)
-        (point-marker)))))
+          (point-marker))))))
 
 (cl-defmethod xref-location-line ((l xref-etags-location))
   (with-slots (tag-info) l