bug#50178: 28.0.50; Size of echo area does not account for line-spacing

[Óscar Fuentes]

Seems that on some circunstances the vertical space calculated for the
text on the echo area does not account for the value of line-spacing:

emacs -Q
M-x icomplete-vertical-mode
M-x fido-mode
(set-default 'line-spacing 0.1)

Now M-x will display a list of candidates with the last candidate
partially visible for lack of vertical space.


In GNU Emacs 28.0.50 (build 4, x86_64-pc-linux-gnu, X toolkit, cairo version 
1.16.0)
 of 2021-07-30 built on sky
Repository revision: d9bc7dbefd88995d04b9843f521d82118265fecf
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Debian GNU/Linux 11 (bullseye)

Configured using:
 'configure --with-native-compilation --without-toolkit-scroll-bars
 --with-x-toolkit=lucid --with-modules --without-imagemagick
 build_alias= host_alias= target_alias='

Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON
LIBOTF LIBSELINUX LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG
RSVG SECCOMP SOUND THREADS TIFF X11 XAW3D XDBE XIM XPM LUCID ZLIB