Merge changes from 3.15 branch into 7.0

- merged 3.15 branch up to bf7a1605

# Conflicts:
#	modules/database/src/ioc/db/dbChannel.c

modules/ca/src/client/access.cpp

@@ -603,7 +603,7 @@ void epicsStdCall ca_signal_formated ( long ca_status, const char *pfilenm,
     }
     else {
         fprintf ( stderr, "CA exception in thread w/o CA ctx: status=%s file=%s line=%d: \n",
-            ca_message ( ca_status ), pfilenm, lineno );
+            ca_message ( ca_status ), pfilenm ? pfilenm : "<null>", lineno );
         if ( pFormat ) {
             vfprintf ( stderr, pFormat, theArgs );
         }