Purecopy removal: Lisp code

* lisp/emacs-lisp/bytecomp.el (byte-compile-cond-jump-table): Don't
request our hash tables be purecopied.  Adjust comment.
* lisp/progmodes/elisp-mode.el (elisp--local-variables-completion-table):
Use 'defconst' rather than 'defvar' now the purespace problem is gone
* lisp/rfn-eshadow.el (file-name-shadow-properties): Remove obsolete
comment.

lisp/emacs-lisp/bytecomp.el

@@ -4640,13 +4640,12 @@ Return (TAIL VAR TEST CASES), where:
                                       cases))))
       (setq jump-table (make-hash-table
 			:test test
-			:purecopy t
 			:size nvalues)))
     (setq default-tag (byte-compile-make-tag))
     ;; The structure of byte-switch code:
     ;;
     ;; varref var
-    ;; constant #s(hash-table purecopy t data (val1 (TAG1) val2 (TAG2)))
+    ;; constant #s(hash-table data (val1 (TAG1) val2 (TAG2)))
     ;; switch
     ;; goto DEFAULT-TAG
     ;; TAG1

lisp/progmodes/elisp-mode.el

@@ -489,11 +489,7 @@ use of `macroexpand-all' as a way to find the \"underlying raw code\".")
                              var))
                       vars))))))
 
-(defvar elisp--local-variables-completion-table
-  ;; Use `defvar' rather than `defconst' since defconst would purecopy this
-  ;; value, which would doubly fail: it would fail because purecopy can't
-  ;; handle the recursive bytecode object, and it would fail because it would
-  ;; move `lastpos' and `lastvars' to pure space where they'd be immutable!
+(defconst elisp--local-variables-completion-table
   (let ((lastpos nil) (lastvars nil))
     (letrec ((hookfun (lambda ()
                         (setq lastpos nil)

lisp/rfn-eshadow.el

@@ -92,7 +92,6 @@
 		  (sexp :tag "Value")))))
 
 (defcustom file-name-shadow-properties
-  ;; FIXME: should we purecopy this?
 '(face file-name-shadow field shadow)
   "Properties given to the `shadowed' part of a filename in the minibuffer.
 Only used when `file-name-shadow-mode' is active.