Septentrio GLO raw canav: avoid subframe time unaligned access

The raw time is stored in the subframe buffer, beyond the data, and
used to invalidate the buffer. Store the time in seconds, truncated
to 32 bits, and use memcpy to read and write this to the buffer.

src/rcv/septentrio.c

@@ -1599,7 +1599,6 @@ static int decode_gpsrawcanav(raw_t *raw, int sys){
 /* decode SBF raw nav message (raw navigation data) for glonass---------------*/
 static int decode_glorawcanav(raw_t *raw){
     geph_t geph = {0};
-    gtime_t *time;
     double utc[8] = {0};
     uint8_t *p = raw->buff+14, buff[12];
     int i, svid, sat, prn, m;
@@ -1629,10 +1628,11 @@ static int decode_glorawcanav(raw_t *raw){
         trace(2, "sbf glorawca string number error: prn=%d m=%d\n", prn, m);
         return -1;
     }
-    time = (gtime_t *)(raw->subfrm[sat-1]+150);
-    if (fabs(timediff(raw->time, *time)) > 30.0) {
+    int32_t time = raw->time.time;
+    int32_t dt = time - I4(raw->subfrm[sat - 1] + 152);
+    if (dt > 30 || dt < -30) {
         memset(raw->subfrm[sat-1], 0, 40);
-        memcpy(time, &raw->time, sizeof(gtime_t));
+        memcpy(raw->subfrm[sat-1]+152, &time, sizeof(time));
     }
     memcpy(raw->subfrm[sat-1]+(m-1)*10, buff, 10);
     if (m != 4) return 0;