[flang] Add support of `-fstrict-aliasing`/`-fno-strict-aliasing`

Some old programs may require to be compiled with `-fno-strict-aliasing` even if they are written in Fortran. It would be nice, if flang will support these options. Currently, it does not: https://godbolt.org/z/c4qKbErbh

Begin with flang and reproduce the current rejection using the linked Godbolt example for both options. Trace flang's handling of these compiler flags and verify that both -fstrict-aliasing and -fno-strict-aliasing are accepted for Fortran programs.

Written by the indexing model from the issue text.