Add ScaLAPACK explicitly

[RMeli]

Building a Spack stack on Santis results in the following issue:

CMake Error at /user-environment/linux-sles15-neoverse_v2/gcc-12.3.0/dla-future-0.4.0-yybav6v7epu7cwhjqfzd7asrgwopoqmq/lib64/cmake/DLAF/DLAF-Targets.cmake:69 (set_targ
et_properties):
  The link interface of target "DLAF::dlaf.prop" contains:

    DLAF::SCALAPACK

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.

Call Stack (most recent call first):
  /user-environment/linux-sles15-neoverse_v2/gcc-12.3.0/dla-future-0.4.0-yybav6v7epu7cwhjqfzd7asrgwopoqmq/lib64/cmake/DLAF/DLAFConfig.cmake:38 (include)
  CMakeLists.txt:626 (find_package)

I haven't yet fully investigated this issue, but possibly related to #1122.

[RMeli]

cscs-ci run

[msimberg]

Given the error in https://gitlab.com/cscs-ci/ci-testing/webhook-ci/mirrors/4700071344751697/7514005670787789/-/jobs/6687067202#L3097, I think this is actually not necessary, at least not in that form... Are you building with nvpl on santis? Perhaps it's not actually finding scalapack for some reason? At least the target should be correctly created if it is found:

DLA-Future/cmake/FindSCALAPACK.cmake

Line 35 in 64b6ddb

add_library(DLAF::SCALAPACK INTERFACE IMPORTED GLOBAL)

.

[RMeli]

Yes, this is definitely not the correct solution. I'll need to investigate further. I have only encountered the issue on Santis, but I'm building with openblas/netlib-scalapack.