bugfix: spack stacks mixed dependency and non-dep constraints (#12315)

Spack stacks drop invalid dependencies applied to packages by a
spec_list matrix operation

Without this fix, Spack would raise an error if orthogonal dependency
constraints and non-dependency constraints were applied to the same
package by a matrix and the dependency constraint was invalid for
that package. This is an error, fixed by this PR.

An example failing configuration:

spack:
  definitions:
  - packages: [libelf, hdf5+mpi]
  - compilers: ['%gcc']
  - mpis: [^openmpi]

  specs:
  - matrix:
    - $packages
    - $compilers
    - $mpis

0 files changed, 0 insertions, 0 deletions