openmpi constraint graph cycle

[tartarini]

in Docker for Centos (and in general installation) select a unique and consistent *MPI installation along petsc and pFire.
For testing of different libraries combinations, it could be worth to install openmpi from source rather than using package manager.

`
-- The following OPTIONAL packages have not been found:

• DCMTK
• OpenImageIO

-- Configuring done
CMake Warning at src/CMakeLists.txt:35 (add_executable):
Cannot generate a safe runtime search path for target pfire because there
is a cycle in the constraint graph:

dir 0 is [/usr/lib64/openmpi/lib]
  dir 1 must precede it due to runtime library [libmpi_usempif08.so.40]
dir 1 is [/local/sandbox/petsc-3.10.5/arch-linux2-c-debug/lib]
  dir 0 must precede it due to runtime library [libmpi.so.40]

Some of these libraries may not be found correctly.
`