Add library names for Fedora (based on Fedora 33)

[mfandl]

Hello,

this PR adds support for Fedora 33, 'fedora is added to the distribution list and blas and fortran libraries are set the following way:

• libcblas.so.3 instead of libblas.so.3 - the correct symbols are exported from the former
• libgfortran.so.5 instead of libgfortran.so.3 - 3 is not available in Fedora, see:

$ dnf provides libgfortran.so.3
Last metadata expiration check: 18:29:56 ago on Fri 11 Dec 2020 09:58:17 PM CET.
Error: No Matches found

These changes are based on Fedora 33 and I am not sure about the granularity. I saw there are no versions for the other distros, so I went for a general 'fedora distribution, although I only tested on 33. Shall I change it to match only 33 and use a more granular way? eg fedora33?

My system is identified by that fc33 part of the following string, I set the regex to expect fc + 2 digits for Fedora.

> (system-type 'machine)
"Linux mrau 5.9.10-200.fc33.x86_64 #1 SMP Mon Nov 23 18:12:50 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Test run:

$ raco test flomat.rkt
raco test: (submod "flomat.rkt" test)
82 tests passed

[soegaard]

Thanks for adding Fedora!

Let's keep it simple for now and just use the current patch (since we don't have access to other Fedora distributions to test on).