Description:
You cannot install scotch on a 2 core cpu

Steps to reproduce:
Run the following commands on a cpu with 2 cores.
$ git clone https://aur.archlinux.org/scotch.git
$ cd scotch
$ makepkg -si

Expected behaviour:
It should install scotch.

Actual behaviour:
The makepkg fails with the following output:
...
mpicc -march=x86-64 -mtune=generic -O2 -pipe -fno-plt -fPIC -DCOMMON_FILE_COMPRESS_GZ -DCOMMON_FILE_COMPRESS_BZ2 -DCOMMON_PTHREAD -DCOMMON_RANDOM_FIXED_SEED -DSCOTCH_RENAME -Drestrict=__restrict -DIDXSIZE64 -DSCOTCH_PTSCOTCH -I../../in
clude -L../../lib test_scotch_dgraph_check.c -o test_scotch_dgraph_check -lptscotch -lscotch -lptscotcherr -lz -lbz2 -lm -lrt -pthread -Xlinker --no-as-needed
mpirun -n 3 ./test_scotch_dgraph_check data/bump.grf
--------------------------------------------------------------------------
There are not enough slots available in the system to satisfy the 3
slots that were requested by the application:

./test_scotch_dgraph_check

Either request fewer slots for your application, or make more slots
available for use.

A "slot" is the Open MPI term for an allocatable unit where we can
launch a process. The number of slots available are defined by the
environment in which Open MPI processes are run:

1. Hostfile, via "slots=N" clauses (N defaults to number of
processor cores if not provided)
2. The --host command line parameter, via a ":N" suffix on the
hostname (N defaults to 1 if not provided)
3. Resource manager (e.g., SLURM, PBS/Torque, LSF, etc.)
4. If none of a hostfile, the --host command line parameter, or an
RM is present, Open MPI defaults to the number of processor cores

In all the above cases, if you want Open MPI to default to the number
of hardware threads instead of the number of processor cores, use the
--use-hwthread-cpus option.

Alternatively, you can use the --oversubscribe option to ignore the
number of available slots when deciding the number of processes to
launch.
--------------------------------------------------------------------------
make[2]: *** [Makefile:309: check_scotch_dgraph_check] Error 1
make[2]: Leaving directory '/home/volker/Sync/DatenVolker/scripts/ArchInstallation/scotch/src/scotch-v6.0.6/src/check'
make[1]: *** [Makefile:74: ptcheck] Error 2
make[1]: Leaving directory '/home/volker/Sync/DatenVolker/scripts/ArchInstallation/scotch/src/scotch-v6.0.6/src/check'
make: *** [Makefile:110: ptcheck] Error 2
==> ERROR: A failure occurred in check().
Aborting...