Don't make faces when loading Custom themes.

Don't make faces when loading Custom themes.

* custom.el (custom-theme-recalc-face): Do nothing if the face is
undefined.  Thus, theme settings for undefined faces do not take
effect until the faces are defined with defface, the same as with
theme variables.

* faces.el (face-spec-set): Use face-spec-recalc in all cases.
(face-spec-reset-face): Don't assign extra properties in temacs.
(face-spec-recalc): Apply X resources too.