Bug#794526: busybox: testsuite is run iff DEB_BUILD_OPTIONS contains nocheck

[Helmut Grohne <helmut@subdivi.de>]

Source: busybox
Version: 1.22.0-15
Severity: important
Tags: patch
User: helmutg@debian.org
Usertags: rebootstrap

During a partial archive cross rebuild, I noticed that busybox FTCBFS,
because it runs its test suite despite being told
DEB_BUILD_OPTIONS=nocheck. This is surprising, because it actually tries
to take care of that flag. Even more surprising (and the reason for
flagging this bug as important) is that the test suite is not run during
native buildd builds.

It turned out that the detection logic has an inversion flaw, so the
test suite is run and only run when DEB_BUILD_OPTIONS contains nocheck.
The attached patch might or might not fix the FTCBFS, but it fixes the
logic inversion.

Helmut