[llvm] r201921 - Use relative rpath so that the installation and build dirs are relocatable.

[Rafael Espíndola]

>> Does it work when building with configure?
>
>
> No, with configure it seems no rpath is set and I need to explicitly set
> LD_LIBRARY_PATH. The cmake behaviour now matches the autoconf behaviour. I
> earlier cmake behaviour was more convenient, but if there are reasons to go
> with the autoconf behaviour we can probably do this.
> In case this is necessary, I can change the buildcommands and ask Galina to
> restart the buildbots on Monday.

I guess you can say the change was intentional then. In general it
seems a bad (but admittedly convenient at times) to bake information
about the build setup in the binaries. What I have done is change the
logic just in polly to record where out of build-dir libraries are
found.

It is up to you if you want to keep that in polly or you want to
switch to using LD_LIBRARY_PATH.

Cheers,
Rafael