Remove some unused code.
[analyzer] Allow suppressing diagnostics reported within the 'std' namespace

This is controlled by the 'suppress-c++-stdlib' analyzer-config flag.
It is currently off by default.

This is more suppression than we'd like to do, since obviously there can
be user-caused issues within 'std', but it gives us the option to wield
a large hammer to suppress false positives the user likely can't work
around.
[analyzer] Use inline storage in the FunctionSummary DenseMap.

The summaries lasted for the lifetime of the map anyway; no reason to
include an extra allocation.

Also, use SmallBitVector instead of BitVector to track the visited basic
blocks -- most functions will have less than 64 basic blocks -- and
use bitfields for the other fields to reduce the size of the structure.

No functionality change.
[analyzer] Cache whether a function is generally inlineable.

Certain properties of a function can determine ahead of time whether or not
the function is inlineable, such as its kind, its signature, or its
location. We can cache this value in the FunctionSummaries map to avoid
rechecking these static properties for every call.

Note that the analyzer may still decide not to inline a specific call to
a function because of the particular dynamic properties of the call along
the current path.

No intended functionality change.
[analyzer] For now, don't inline [cd]tors of C++ containers.

This is a heuristic to make up for the fact that the analyzer doesn't
model C++ containers very well. One example is modeling that
'std::distance(I, E) == 0' implies 'I == E'. In the future, it would be
nice to model this explicitly, but for now it just results in a lot of
false positives.

The actual heuristic checks if the base type has a member named 'begin' or
'iterator'. If so, we treat the constructors and destructors of that type
as opaque, rather than inlining them.

This is intended to drastically reduce the number of false positives
reported with experimental destructor support turned on. We can tweak the
heuristic in the future, but we'd rather err on the side of false negatives
for now.

<rdar://problem/13497258>