install *.pc below CMAKE_INSTALL_DATADIR

[anbe42]

Since these headers are architecture independent, please install the pkgconfig file in the architecture independent location below CMAKE_INSTALL_DATADIR (effectively /usr/share/pkgconfig/) like it is already done with the *.cmake files instead of the architecture dependent location below CMAKE_INSTALL_LIBDIR (on Debian/amd64 /usr/lib/x86_64-linux-gnu/pkgconfig/)

May affect the clhpp headers, too.

[Kerilk]

@anbe42 Thanks for the feeback, I'll prepare a series of pull request to implement this.

[Kerilk]

@anbe42 PRs are ready. I do have a couple of questions for you:

• We could either do a fix release, or wait for IWOCL (mid April) to release those changes. Any preference?
• What would you advise for the C++ headers? Should we add their own pkg-config file that would depend on the OpenCL headers one? Until now we considered they would be installed alongside each other, but given the direction we took by splitting loader and headers, maybe we should go all the way.

Thanks

[Kerilk]

@anbe42 We've pushed the various fixes. We also added a .pc file to the C++ headers. please tell me if this looks good to you or if further actions should be taken.