Skip sched/priority tests

These tests try to change the priority of the running process, but if
e.g. PORTAGE_NICENESS=19, you can't spawn a process with lower (or higher!)
niceness, as there's nowhere to go. Ditto priorities.

Signed-off-by: Sam James <sam@gentoo.org>

Author: thesamesam

Lib/test/test_os/test_posix.py

@@ -2097,6 +2097,7 @@ def test_setsigdef_wrong_type(self):
                             os.environ, setsigdef=[signal.NSIG, signal.NSIG+1])
 
     @requires_sched
+    @unittest.skip('Gentoo: fails when PORTAGE_NICENESS is set')
     @unittest.skipIf(sys.platform.startswith(('freebsd', 'netbsd')),
                      "bpo-34685: test can fail on BSD")
     def test_setscheduler_only_param(self):
@@ -2117,6 +2118,7 @@ def test_setscheduler_only_param(self):
         support.wait_process(pid, exitcode=0)
 
     @requires_sched
+    @unittest.skip('Gentoo: fails when PORTAGE_NICENESS is set')
     @unittest.skipIf(sys.platform.startswith(('freebsd', 'netbsd')),
                      "bpo-34685: test can fail on BSD")
     @unittest.skipIf(platform.libc_ver()[0] == 'glibc' and