Compilation fix for libjpeg release 9

In the latest libjpeg version, the "boolean" type is changed so that
true and false no longer can be used instead of TRUE and FALSE.

Also, purge some ancient code remains meant to support a now defunct
OS´s idea about the boolean type.

Task-number: QTBUG-33166
Change-Id: Iebbdf300cfdc22775954de65f985358424ed2b49
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>