memory: Small changes to fix some memory leaks.

Four small leaks in *scam, sx1276, and ozw.  Added calls to
cleanup resources before throws.

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/sx1276/sx1276.cxx

@@ -151,6 +151,7 @@ SX1276::SX1276(uint8_t chipRev, int bus, int cs, int resetPin, int dio0,
   
   if (pthread_mutex_init(&m_intrLock, &mutexAttrib))
     {
+      pthread_mutexattr_destroy(&mutexAttrib);
       throw std::runtime_error(std::string(__FUNCTION__) +
                                ": pthread_mutex_init(intrLock) failed");
     }