Enable the default fontset to use

Enable the default fontset to use
unicode fonts for ASCII characters.
(x-decompose-font-name): Don't try to resolve PATTERN by
x-resolve-font-name.
(x-complement-fontset-spec): Never prepend an ASCII font.
(create-fontset-from-fontset-spec): If a fontset of the same name
already exists, override it instead of signalling an error.  Don't
turn `ascii' into `latin'.  Don't update fontset-alias-alist here.