package/python-iptables: try known libc instead of find_library()

package/python-iptables: try known libc instead of find_library()

ctypes.util.find_library() depends on gcc and friends to detect the location of
a given shared library. Given that these are not available on the target and
that python-iptables depends on this functionality we need to work around this.
The SONAMEs of the libc are well known so we try the known ones for glibc,
uClibc and musl.

Fixes: https://bugs.busybox.net/show_bug.cgi?id=12271
Signed-off-by: Frank Vanbever <frank.vanbever@essensium.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>