Remove slurmdb from libs to link against for newer Slurm versions (>18)

[EricR86]

This PR removes the libslurmdb library only in newer versions of SLURM as it was merged in with libslurm on versions of SLURM past 18.

The details of this change can be found under the "28 May 2019" section of the RELEASE_NOTES and can be found on the website.

Additionally, this also fixes a configure option when using --with-slurm-lib to point at a custom directory for SLURM libraries. Since this directory also contains the runtime libraries, the test in configure now includes that directory for runtime linking when testing the SLURM test program after compilation.

Fixes Issue #28

[natefoo]

I'm guessing this will need to be conditional based on the version of Slurm detected by autoconf?

[EricR86]

Depends if you want it to be conditional in the first place. This original fork presumably does not work with older versions of SLURM anyway correct?

It is possible just to make it conditional whether or not the slurmdb library is found though I'll have a hard time testing since I don't have access to both SLURM versions. Would you still prefer to build releases for both SLURM 19 and 18?

[natefoo]

This fork currently works with Slurm >= 16.05. I don't think we need to maintain compatibility back that far for new releases, but supporting at least the current oldest supported version of Slurm (18.08) would be ideal.

You can build a local copy of Slurm for testing, or if you don't want to invest any additional time, I can pick it up from here (but it'll probably be a week or so before I can do that).

[EricR86]

@natefoo sorry for taking so long to get to this but I believe I have created a fix that is now compatible with all versions of SLURM. It's ready for your review and approval.

[holtgrewe]

Hi, is there any news on this? I'd really like to get a slurm-drmaa that is compatible with slurm 20.x.

[natefoo]

@EricR86 Thanks, this looks good to me. I'll merge and make a new release shortly.