Handle 1D arrays for MPI_Ssend and Add Test for MPI_WaitAll

[adit4443ya]

No description provided.

[adit4443ya]

Lfortran is giving segfault while rest of the tests passes , will investigate later

[gxyd]

At the CI, even the job Run standalone tests with MPICH without custom MPI Wrappers (ubuntu-20.04) failed, which is odd. Atleast this job has nothing to do with LFortran.

I checked it locally on my macOS, and it passes with MPICH without custom MPI wrappers.

[gxyd]

Also, I checked it with LFortran as well, and waitall_1.f90 seems to work without any problem locally on macOS:

> ./run_tests.sh waitall_1.f90
#################################
Using FC=/Users/gxyd/miniforge3/envs/pot3d_build/bin/lfortran compiler
Using CC=clang compiler
################################

Received argument(s). Will only compile/run: waitall_1.f90
Compiling waitall_1...
Running waitall_1 with 1 MPI ranks...
This test requires at least 2 MPI processes.
Test waitall_1 with 1 MPI ranks PASSED!
Running waitall_1 with 2 MPI ranks...
Rank 1 received buf1 =    1.00000000000000000e+00    2.00000000000000000e+00    3.00000000000000000e+00    4.00000000000000000e+00    5.00000000000000000e+00    6.00000000000000000e+00    7.00000000000000000e+00    8.00000000000000000e+00    9.00000000000000000e+00
Rank 1 received buf2 =    1.00000000000000000e+00    2.00000000000000000e+00    3.00000000000000000e+00    4.00000000000000000e+00    5.00000000000000000e+00    6.00000000000000000e+00    7.00000000000000000e+00    8.00000000000000000e+00    9.00000000000000000e+00
Rank 0 sent two messages.
Test waitall_1 with 2 MPI ranks PASSED!
Running waitall_1 with 4 MPI ranks...
Rank 0 sent two messages.
Rank 1 received buf1 =    1.00000000000000000e+00    2.00000000000000000e+00    3.00000000000000000e+00    4.00000000000000000e+00    5.00000000000000000e+00    6.00000000000000000e+00    7.00000000000000000e+00    8.00000000000000000e+00    9.00000000000000000e+00
Rank 1 received buf2 =    1.00000000000000000e+00    2.00000000000000000e+00    3.00000000000000000e+00    4.00000000000000000e+00    5.00000000000000000e+00    6.00000000000000000e+00    7.00000000000000000e+00    8.00000000000000000e+00    9.00000000000000000e+00
Test waitall_1 with 4 MPI ranks PASSED!

... Running standalone tests took 4 seconds ...

> echo $?
0

[gxyd]

Even the tests that I added, fail #90