ScaLAPACK fails with GCC 10

[MarcusCalhoun-Lopez]

By default, the about to be released GCC 10 is more strict about Fortran argument types.

When attempting to build ScaLAPACK with GCC 10, compiling BLACS code produced many errors of the type

Rank mismatch between actual argument at (1) and actual argument at (2)

The errors were reduced to warning by adding -fallow-argument-mismatch to gfortran.

[julielangou]

#26 should fix this issue.