Revert "Copy structs using assignment, not memcpy()."

This reverts commit d1965788249d7e22cdde4021d452cf0dc6c6b9bd.

This breaks my build on Gentoo running gcc 4.9.2

libgps_shm.c: In function 'int gps_shm_read(gps_data_t*)':
libgps_shm.c:122:12: error: no match for 'operator=' (operand types are
'gps_data_t' and 'volatile gps_data_t')
  noclobber = shared->gpsdata;
            ^
libgps_shm.c:122:12: note: candidate is:
In file included from gpsd.h:350:0,
                 from libgps_shm.c:30:
gps.h:1918:8: note: gps_data_t& gps_data_t::operator=(const gps_data_t&)
 struct gps_data_t {
        ^
gps.h:1918:8: note:   no known conversion for argument 1 from 'volatile
gps_data_t' to 'const gps_data_t&'

1 files changed, 3 insertions, 1 deletions

diff --git a/gpsctl.c b/gpsctl.c
index fc588123..655999ad 100644
--- a/gpsctl.c
+++ b/gpsctl.c
@@ -400,7 +400,9 @@ int main(int argc, char **argv)
 	    exit(EXIT_FAILURE);
 	devicelist_entry_matches:;
 	}
-	gpsdata.dev = gpsdata.devices.list[i];
+	(void)memcpy(&gpsdata.dev,
+		     &gpsdata.devices.list[i],
+		     sizeof(struct devconfig_t));
 	devcount = gpsdata.devices.ndevices;
 
 	/* if the device has not identified, watch it until it does so */