test fgsl_linalg_qrpt_lssolve2 in linalg fails

[reinh-bader]

build with ifx causes one test in linalg (fgsl_linalg_qrpt_lssolve2:x) to fail

Intel(R) Fortran Compiler for applications running on Intel(R) 64, Version 2024.0.2 Build 20231213
OS: Ubuntu 20.04.6 LTS / executing under WSL 2

[reinh-bader]

Depending on compiler and platform, the solution vector oscillates between [ 2.,-1.,0.] and [1.,0.,1.]. Further investigation will be needed.

[reinh-bader]

Further observation: It is already the prior call to fgsl_linalg_qrpt_decomp with a rank-deficient argument a that produces divergent results. The test is commented out for now. Next step would be to reproduce this in C.