Merge remote-tracking branch 'zimoch/iocLogClientFixesTry2' into 7.0

* zimoch/iocLogClientFixesTry2: (22 commits)
  use EPICS_PRIVATE_API macro and fix bug with darwin/ios
  renamed epicsSocketCountUnsentBytes to epicsSocketUnsentCount and moved it to osi/os/
  fix bug from commit f85454. Apparently epicsExportSharedSymbols is needed even though epicsExport.h is included
  epicsSocketCountUnsentBytes returns -1 on failure
  bugfix: memmove'ed to much
  epicsSockCountUnsentBytes renamed to epicsSocketCountUnsentBytes
  moved logClientSendMessage and made it static
  fix wrong function name in comment
  sending 0 bytes helps to detect broken connections on some systems (but is undefined behavior on Linux, fails on vxWorks and is a documented no-op on Windows)
  cannot print sockets with %d in Windows, they are not small ints but maybe pointers.
  ask logClient socket how many bytes are still in the send queue and don't discard them in case the connection turns out broken.
  use dynamic debug flag for logClient
  increase error message buffer size for long (Windows) error messges
  improve logClientShow to show unsent bytes on level 2 (and fix level 1)
  removed unneeded include
  no need to delay startup only because log server is currently not available
  send pending log messages directly after connecting
  avoid needless memmove calls
  elimitate duplicate code in logClient
  do not discard unsent messages when log server has closed connection, instead try to send them after reconnect
  ...

modules/database/src/ioc/misc/dbCore.dbd

@@ -33,3 +33,6 @@ variable(callbackParallelThreadsDefault,int)
 
 # Real-time operation
 variable(dbThreadRealtimeLock,int)
+
+# show logClient network activity
+variable(logClientDebug,int)