No Signal/Noise and no Signal Strength with Si2168-based tuners

The Linux driver for the Si2168 only implements the DVBv5 calls
to retrieve the signal strength etc.
The MythTV code first tries the DVBv3 call and if that fails
with an EOPNOTSUPP then the DVBv5 call is tried.
This worked correct until Linux kernel changed the
error code from EOPNOTSUPP to ENOTSUPP (value 524).
This fix adds a test on ENOTSUPP in addition to the existing
test on EOPNOTSUPP.

mythtv/libs/libmythtv/recorders/dvbchannel.cpp

@@ -49,6 +49,11 @@
 #include "dvbcam.h"
 #include "tv_rec.h"
 
+// Returned by drivers on unsupported dvbv3 ioctl calls
+#ifndef ENOTSUPP
+#define ENOTSUPP 524
+#endif
+
 static void drain_dvb_events(int fd);
 static bool wait_for_backend(int fd, int timeout_ms);
 static struct dvb_frontend_parameters dtvmultiplex_to_dvbparams(
@@ -1159,7 +1164,7 @@ double DVBChannel::GetSignalStrength(bool *ok) const
     if (ret < 0)
     {
 #if DVB_API_VERSION >=5
-        if (errno == EOPNOTSUPP)
+        if (errno == EOPNOTSUPP || errno == ENOTSUPP)
         {
             return GetSignalStrengthDVBv5(ok);
         }
@@ -1247,7 +1252,7 @@ double DVBChannel::GetSNR(bool *ok) const
     if (ret < 0)
     {
 #if DVB_API_VERSION >=5
-        if (errno == EOPNOTSUPP)
+        if (errno == EOPNOTSUPP || errno == ENOTSUPP)
         {
             return GetSNRDVBv5(ok);
         }
@@ -1318,7 +1323,7 @@ double DVBChannel::GetBitErrorRate(bool *ok) const
     if (ret < 0)
     {
 #if DVB_API_VERSION >=5
-        if (errno == EOPNOTSUPP)
+        if (errno == EOPNOTSUPP || errno == ENOTSUPP)
         {
             return GetBitErrorRateDVBv5(ok);
         }
@@ -1382,7 +1387,7 @@ double DVBChannel::GetUncorrectedBlockCount(bool *ok) const
     if (ret < 0)
     {
 #if DVB_API_VERSION >=5
-        if (errno == EOPNOTSUPP)
+        if (errno == EOPNOTSUPP || errno == ENOTSUPP)
         {
             return GetUncorrectedBlockCountDVBv5(ok);
         }
@@ -1507,6 +1512,8 @@ static bool wait_for_backend(int fd, int timeout_ms)
 
     // This is supposed to work on all cards, post 2.6.12...
     fe_status_t status;
+    memset(&status, 0, sizeof(status));
+
     if (ioctl(fd, FE_READ_STATUS, &status) < 0)
     {
         LOG(VB_GENERAL, LOG_ERR,