Bug#939949: sleepyhead: B-D on cruft package

[Esa Peuha]

Source: sleepyhead
Version: 1.0.0-beta-2+dfsg-6
Severity: serious

Currently sleepyhead build-depends on libquazip5-headers, which is
no longer built from source as its contents have been merged into
libquazip5-dev, thus making sleepyhead unbuildable since these two
packages are not coinstallable. Please remove the build-dependency
on libquazip5-headers.