The GLPK exact solver ignores msg_lev
and prints a lot of things on the screen while solving (see tests in #20424).

sage: p = MixedIntegerLinearProgram(solver="GLPK/exact")
sage: p.get_backend().set_verbosity(0)
sage: TestSuite(p.get_backend()).run(skip="_test_pickling")
glp_exact: 5 rows, 1 columns, 4 non-zeros
GNU MP bignum library is being used
...

Reported upstream:

1. http://lists.gnu.org/archive/html/help-glpk/2011-10/msg00037.html

2. http://lists.gnu.org/archive/html/bug-glpk/2017-08/msg00013.html

Depends on #23596

Upstream: Fixed upstream, but not in a stable release.

CC: @kiwifb @jdemeyer @dimpase @videlec

Component: packages: standard

Keywords: glpk

Author: Jeroen Demeyer

Branch/Commit: 4f4fa2c

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/20876