server search handling uses unguarded global map

[mdavidsaver]

I'd noticed s_channelNameToProvider before, I hadn't noticed that it is static. So in addition to not being guarded from concurrent access, it allows cross-talk between separate servers operating within the same process (aka a gateway).

pvAccessCPP/src/server/pv/responseHandlers.h

Lines 120 to 121 in 3b565d0

	// TODO
	static std::map<std::string, std::tr1::weak_ptr<ChannelProvider> > s_channelNameToProvider;

[mdavidsaver]

I also missed a third problem, that this code was using ServerSearchHandler::s_channelNameToProvider[channelName].lock() w/o considering that operator[] implicitly insert()s when name doesn't exist. In this case a NULL weak_ptr. An that lock() returns NULL instead of throwing. So attempting to createChannel() for a name which never had a successful search would crash was well.

All three aspects should be fixed by 12e7b78

[mdavidsaver]

Released with Base 7.0.2