WinlFlow.c: add log errors for more failure cases

Every time a flow command fails unexpectedly, we should output to
the debugger a log error. This would make debugging and testing easier
in cases of failures.
Improve logging for WinlFlow

o) Debug functions such as DbgPrintFlowWithActions take many parameters.
Use macros that call such functions instead, for specific peculiarities
(e.g. have a flow, or have a flow match)
o) If OVS_DBGPRINT_FLOW is not #define-d, the macros should be defined as
DEBUGP with given log level: this way, we don't have to duplicate logs --
i.e., once to put a DEBUGP(LOG_ERROR, ...) and again to put a DBGPRINT_FLOW(...)
for advanced debug output.
Use DBGPRINT_FLOW in WinlFlow

If OVS_DBGPRINT_FLOW is #define-d, the flow info (i.e. packet info,
mask, actions) will be logged. Otherwise, the flow itself will not
be printed, but the message will be passed to DEBUGP with the given
log level.

OVS_DBGPRINT_FLOW is useful when we need to debug problems in the
management of the flows.
Fix compilation errors for release mode

All OVS_CHECK_* macros must be #define-d, on both debug and
release modes.