--without-knem (and --with-knem=no) builds knem anyways

[alphataubio]

Background information

What version of Open MPI are you using? (e.g., v4.1.6, v5.0.1, git branch name and hash, etc.)

5.0.5

Describe how Open MPI was installed (e.g., from a source/distribution tarball, from a git clone, from an operating system distribution package, etc.)

wget https://download.open-mpi.org/release/open-mpi/v5.0/openmpi-5.0.5.tar.gz
tar xzvf openmpi-5.0.5.tar.gz; cd openmpi-5.0.5

Please describe the system on which you are running

OS: Linux "Rocky Linux 8.10 (Green Obsidian)" 4.18.0-553.16.1.el8_10.x86_64 x86_64

Compiler: GNU C++ 12.3.1 20230526 with OpenMP 4.5
C++ standard: C++17

Network: Mellanox Infiniband EDR (100 Gb/s)
module load cuda/12.2 pmix/5.0.2 prrte/3.0.5

---

Details of the problem

./configure --prefix=$HOME/local/openmpi-5.0.5 --with-cuda=$CUDA_HOME
--with-cuda-libdir=$CUDA_HOME/lib64/stubs --with-knem=no
--disable-io-romio --with-io-romio-flags=--without-ze ; make -j 8 all; make install

BUT KNEM GETS BUILT ANYWAYS !?

--- MCA component smsc:knem (m4 configuration macro)
checking for MCA component smsc:knem compile mode... static
checking for knem_io.h... yes
checking for recent version of knem ABI... yes
checking if MCA component smsc:knem can compile... yes

and then

--------------------------------------------------------------------------
WARNING: Open MPI failed to open the /dev/knem device due to a local
error. Please check with your system administrator to get the problem
fixed, or set the smsc MCA variable to "^knem" to silence this warning
and run without knem support.

Open MPI will try to fall back on another single-copy mechanism if one
is available.  This may result in lower performance.

  Local host: beluga1
  Errno:      2 (No such file or directory)
--------------------------------------------------------------------------