tour: ignore pageup and pagedown if ctrl is pressed
tour: ignore pageup and pagedown if ctrl is pressed

Fixes golang/go#11963

Change-Id: I5fb1e598042daa0a3c9137468fae9e7ce55dbce7
Reviewed-on: https://go-review.googlesource.com/13137
Reviewed-by: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

bbandaru/tour,zorion/go-tour-ca,bbandaru/tour,raindev/tour,scryner/tour,golians/tour,LaPingvino/go-tour-nl,phoorichet/tour,shuLhan/tour,LaPingvino/go-tour-nl,dupoxy/go-tour-fr,shuLhan/tour,shuLhan/go-tour-id,zorion/go-tour-ca,shuLhan/go-tour-id,shuLhan/tour,dupoxy/go-tour-fr,tamnd/tour,campoy/go-tour-ua,bbandaru/tour,raindev/tour,campoy/go-tour-ua,dupoxy/go-tour-fr,LaPingvino/go-tour-eo,LaPingvino/go-tour-nl,LaPingvino/go-tour-eo,scryner/tour,tamnd/tour,golians/tour,phoorichet/tour,Go-zh/tour,shuLhan/go-tour-id,phoorichet/tour,Go-zh/tour,raindev/tour,Go-zh/tour,scryner/tour,Go-zh/tour,golians/tour,campoy/go-tour-ua,scryner/tour,LaPingvino/go-tour-eo,golang/tour,tamnd/tour