Delete variable pure-space-overflow

* lisp/startup.el (pure-space-overflow): Make variable obsolete.
* lisp/loadup.el (pure-space-overflow): Do not set.  Remove call to
`garbage-collect', as that is done by `dump-emacs-portable'.

lisp/loadup.el

@@ -565,9 +565,6 @@ directory got moved.  This is set to be a pair in the form of:
 ;; Avoid error if user loads some more libraries now.
 (setq purify-flag nil)
 
-(if (null (garbage-collect))
-    (setq pure-space-overflow t))
-
 ;; Make sure we will attempt bidi reordering henceforth.
 (setq redisplay--inhibit-bidi nil)
 

lisp/startup.el

@@ -427,9 +427,6 @@ from being initialized."
 
 (defvar no-blinking-cursor nil)
 
-(defvar pure-space-overflow nil
-  "Non-nil if building Emacs overflowed pure space.")
-
 (defcustom tutorial-directory
   (file-name-as-directory (expand-file-name "tutorials" data-directory))
   "Directory containing the Emacs TUTORIAL files."