bug#18369: 24.4.50; interactive spec of `facemenu-add-face'

[Drew Adams]

The interactive use of this command is not as convenient as it could be.
Is there a good reason for this?

Why does the interactive spec use "*xFace: \nr" (reading a sexp, no
completion etc.)?  Why does it not use `read-face-name', as does
`facemenu-set-face' (which calls `facemenu-add-face')?

In GNU Emacs 24.4.50.1 (i686-pc-mingw32)
 of 2014-08-15 on LEG570
Bzr revision: 117706 rgm@gnu.org-20140815043406-p5hbu97cbm7pulcn
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --enable-checking 'CFLAGS=-O0 -g3' CPPFLAGS=-DGLYPH_DEBUG=1'