package/connman: disable for musl toolchains

package/connman: disable for musl toolchains

Connman doesn't build with musl toolchains due to several "classic"
musl issues [1] (mixes userspace and kernel headers, missing header)

Upstream received some fixes [2] but they are not yet merged.

Also, gresolv.c use res_ninit() function which is not available
with musl. A fix from Alpinelinux is available [3] but it require
some invasive changes.

Disable connman for musl toolchains for now, and wait for upstream
fixes.

[1] http://wiki.musl-libc.org/wiki/FAQ
[2] https://lists.01.org/pipermail/connman/2016-August/000880.html
    https://lists.01.org/pipermail/connman/2016-August/000881.html
    https://lists.01.org/pipermail/connman/2016-August/000882.html
[3] https://github.com/openembedded/openembedded-core/commit/d08f9d7145ba14ce9fbf320719c05560be69212f

Fixes:
http://autobuild.buildroot.net/results/e88/e88b4dbd4b79fc983b8f7d33da3287966854f8ca
[...]

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>