python3: Address failing ptests on musl

python3: Address failing ptests on musl

Take a partial patch to disable portion of test_makedev, its also applied
in alpine. NODEV does not exist on musl

Add test_null_dlsym to ignore list on musl, it needs GNU ifunc support
and musl does not implement GNU ifuncs

fixes
Failed ptests:
{'python3': ['test_null_dlsym', 'test_makedev', 'python3']}

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>