audio/openal obsolete. please make the changes for x11/qt5-qtmultimedia

[Adrien Fernandes <adrien_fernandes2%hotmail.com@localhost>]

Hello pkgsrc users,

Kamil told me that audio/openal shouldn't be used anymore.
It causes conflicts with audio/openal-soft which will be
required by recent Wine packages and any other future softwares.

We should replace
	.include "../../audio/openal/buildlink3.mk"
by
	.include "../../audio/openal-soft/buildlink3.mk"
in the x11/qt5-qtmultimedia/{Makefile,buildlink3.mk}