Crash if using -v upnp

[Nigel]

On OS X, something funky happens if setting -v upnp (I tried all the -v flags to be sure):

MacBook% ../bin/mythshutdown -v mheg 
mythshutdown: Could not initialize myth context. Exiting.
MacBook% ../bin/mythshutdown -v upnp
mythshutdown: Could not initialize myth context. Exiting.
zsh: bus error  ../bin/mythshutdown -v upnp

probably something in libmythupnp, but could also be MythContext. Stack trace outside of GDB looks corrupt. Running under GDB does not crash. Going to have to do this the hard way.

[Nigel]

In libmythupnp, I changed all the VB_UPNP to VB_EIT. Problem went away. I changed them back to VB_UPNP. Problem returned. Went file by file, narrowed it down to the VERBOSE lines in SSDPCache::~SSDPCache() and UPnpDeviceDesc::~UPnpDeviceDesc().
Several tweaks later, the problem has magically gone away. Will assume this was some sort of freak build/cache/cosmic-ray problem?

[paulh]

I'm sure there is something wrong somewhere :-(

When looking at ticket #4664 I noticed mythshutdown was segfaulting if I added the upnp verbose flag. I'll attach the bt in case you find it useful. As you can see it looks like something is wrong in the SSDPCache destructor. I works OK so long as I don't add upnp to the verbose flags.

[paulh]

backtrace of SSDPCache segfault

[stuartm]

I think we can problem comment or remove the VERBOSE from the SSDPCache dtor, at least for 0.21?

[Nigel]

(In [16049]) Avoid crash when using -v upnp. Closes #4675