package/gpsd: add config option for Spectratime iSync and build fix patch

package/gpsd: add config option for Spectratime iSync and build fix patch

As in the inital 3.17 version bump patch the iSync config option was not
added, the iSync driver was implicitly enabled in the gpsd config as default,
and due to a bug in the gpsd build setup, this caused several autobuild issues
which are fixed by this. This commit adds both the Buildroot config option and
the gpsd patch which was also sent to and accepted in upstream.

Fixes:
    http://autobuild.buildroot.net/results/555b4bdd1707aa21e6d3014e30b635c96c5efffc
    http://autobuild.buildroot.net/results/cfc14a2c471c63ecc4c95c12b8e00ed7656acfd2
    http://autobuild.buildroot.net/results/2104e15526bd6f467f0d56dee10b5fa46e2c71dd
    http://autobuild.buildroot.net/results/610b3f898b396c1def682b809482408c2c4555bc
    ... and many more.

Signed-off-by: Zoltan Gyarmati <mr.zoltan.gyarmati@gmail.com>
Reviewed-by: Matt Weber <matthew.weber@rockwellcollins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>