Fix conform linknamespace tests due to gnu_dev_makedev

If building on s390 / i686 with -Os, various conformance
tests are failing with e.g.
conform/ISO/assert.h/linknamespace.out:
[initial] __assert_fail -> [libc.a(assert.o)] __dcgettext -> [libc.a(dcgettext.o)] __dcigettext -> [libc.a(dcigettext.o)] __getcwd -> [libc.a(getcwd.o)] __fstatat64 -> [libc.a(fstatat64.o)] gnu_dev_makedev

The usage of gnu_dev_makedev was recently introduced by
usage of the makedev makro in commit:
5b980d48
linux: Use statx for MIPSn64

This patch is now linking against __gnu_dev_makedev as
also done in commit:
8b4a1182
Fix -Os gnu_dev_* linknamespace, localplt issues (bug 15105, bug 19463).