Fix test failing with vsdebug build

[joachimmetz]

Tweaked context tests seem to time out on VS 2010 build
https://ci.appveyor.com/project/libyal/libcaes/build/job/gfdyu1ejlc2gwyua

[joachimmetz]

After changes to appveyor configuration (https://ci.appveyor.com/project/libyal/libcaes/builds/46740517) appears to be related to vsdebug. Unable to reproduce locally