face samples in custom should reflect their attributes

[Drew Adams]

emacs -q
customize-face region (or whatever)

The overall sample of the face is fine, but the samples shown for
individual attributes should show only those attributes. For example,
the Background attribute should not show a sample of the color used
only as foreground, which is currently the case.


In GNU Emacs 22.0.50.1 (i386-mingw-nt5.1.2600)
 of 2005-06-26 on NONIQPC
X server distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc
(3.3) --cflags -I../../jpeg-6b-3/include -I../../libpng-1.2.8/include -I../.
./tiff-3.6.1-2/include -I../../xpm-nox-4.2.0/include -I../../zlib-1.2.2/incl
ude'