bug#32276: char-width of a space is 0 when display-table entry has a face.

[Keith David Bershatsky]

Step 1:  Open a newly built GUI version of Emacs master branch.

Step 2:  Open a scratch buffer and evaluate the following code:

;;; char-width == 0
(progn
  (fundamental-mode)
  (setq buffer-display-table (make-display-table))
  (aset buffer-display-table
        ?\s
        (vector (make-glyph-code ?· 'font-lock-warning-face)))
  (char-width ?\s))

Step 3:  The char-width in Step 2 is 0.

Step 4:  In the same or a different scratch buffer, evaluate the following code:

;;; char-width == 1
(progn
  (fundamental-mode)
  (setq buffer-display-table (make-display-table))
  (aset buffer-display-table
        ?\s
        (vector (make-glyph-code ?·)))
  (char-width ?\s))

Step 5:  The char-width in Step 4 is 1.

EXPECTED RESULT:  The char-width should be 1 in Step 2, just like in Step 4.