package/openzwave: set back -fPIC

package/openzwave: set back -fPIC

Set back -fPIC in CFLAGS which was wrongly removed as a side effect of
commit c5ca521e232eae31276e7a12d17f0cf9d9c0108f.

Another side-effect of that commit was to remove
-DSYSCONFDIR="\"$(PREFIX)/etc/openzwave/\"" - however, we don't need
SYSCONFDIR to be set, since /etc/openzwave is checked first anyway (see
cpp/src/Options.cpp).

Fixes:
 - http://autobuild.buildroot.org/results/161f53574697016ab8bdb91aaaf4a2be5410ebb0

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>