package/netsnmp: drop our custom config script fixups

package/netsnmp: drop our custom config script fixups

Those custom fixups were added in 2011 with commit d1b42b24b88
(net-snmp: fixup paths in net-snmp-config) before we add generic config
scripts fixups in 2013 with commit 834f9311aac (pkg-infra: add
<pkg>_CONFIG_FIXUP to fix *-config files)

These custom fixups enclose the includes and libraries paths in single
quotes (presumably to protect them from further expnasion by the shell,
in case there are spaces for example).

It turns out that this breaks now that we replace the staging dir with
$(dirname $0), as it is between single quotes.

It looks like these fixups are really no longer needed anymore, since
the generic fixups do the job just fine (and better).

Fixes:
    http://autobuild.buildroot.org/results/2c5/2c5e379a06825bf8588bf070d733d2e1f98dab66/
    http://autobuild.buildroot.org/results/eea/eea704463c3f14dbb9bd7f8aa23d4b61c25987f4/

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>