dev-libs/gecode: revision bump fixing numerous QA violations

dev-libs/gecode: revision bump fixing numerous QA violations

* Add missing dependencies

* Avoid hard-coded CFLAGS

* Do not install examples to system root

* Install HTML documentation to the correct directory

* Remove unused test USE flag

* Do not allow sci-libs/mpir as a runtime alternative to sci-libs/mpir. This
can only be selected at build time.

* Force building libgecodegist.so against Qt 4 again. Careful consideration must
be given to reverse dependencies before switching to Qt 5 due to the potential
for symbol collisions and ABI breakage. Additionally, the existing approach
is not valid because Qt versions are not interchangeable at runtime.

Gentoo-bug: 488150
Gentoo-bug: 595442

Package-Manager: portage-2.3.1