Arch Linux

Description:
The `.pc` file for LHAPDF is not pointing to the right directories.
In particular the root directory for the data is set as `/usr/share` while the root directory for the installed LHAPDF is `/usr/share/lhapdf` (and the PDFs themselves are installed to `/usr/share/lhapdf/LHAPDF`

If you install LHAPDF from sources the prefix is set to `/usr/share` (or rather `{PREFIX}/share`) as well but in that case the pdfs are installed into `/usr/share/LHAPDF` as expected.


Additional info:
* version 6.4.0

Steps to reproduce:
`lhapdf-config --datadir` points to `/usr/share/lhapdf/LHAPDF`
while
`pkgconf lhapdf --variable=datarootdir` points to `/usr/share` (and it should point to `/usr/share/lhapdf`)

I guess the issue is that --datadir and --datarootdir are actually two separate variables for `lhapdf` (and so, fairly enough, they produce different results). Maybe the best solution is to ensure that during installation they are pointing to compatible folders, something like: `./configure --datadir=/usr/share/lhapdf/LHAPDF --datarootdir=/usr/share/lhapdf`