Please support Ctrl-Alt-= to zoom in

With the GTK3 interface, qemu-system supports pressing Ctrl-Alt-plus
to zoom in and Ctrl-Alt-minus to zoom out.  However, unlike many
programs that support similar zoom hotkeys, qemu-system actually
requires using '+', making the hotkey Ctrl-Alt-Shift-= .  Most programs
with similar zoom hotkeys allow Ctrl-Alt-= as a synonym.

Please consider accepting Ctrl-Alt-= as an additional zoom-in hotkey.

(Observed in QEMU 2.8)

http://git.qemu.org/?p=qemu.git;a=commitdiff;h=66f6b82bf26cc15e33