Cannot build Code_Saturne with PETSc

I have been unable to build Code_Saturne with PETSc for any combination of configure petsc-related options because the relative m4 file is simply wrong, at least for a regular system-wide installation of the petsc package using a typical Linux repository. I modified some files attached here to make it work.

On my system with these modifications and the command line options:

--with-petsc=/usr
--with-petsc-lib=/usr/lib64/openmpi/lib

the compilation works correctly.

You may want to consider updating them.

[cs_petsc.zip](https://github.com/code-saturne/code_saturne/files/3487271/cs_petsc.zip)