Merge integrity support into unix.

Merge integrity support into unix.

Similarly to ec9ea7f3e819cb0c2da8c8977f9cc44688c9b6f6, the code in unix
(non-Linux/OS X) is actually the same as for integrity, so merge the
conditionals together to save duplication.

This should have the side-effect of unbreaking Qt 5 on integrity wrt
the new QStandardPaths introduction, which was not added to the integrity
block.

Change-Id: Ib512fa781f5ceb240069888ce6958c9af2990d37
Reviewed-by: Rolland Dudemaine <rolland@ghs.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>