Enable intercepting (de-)allocated types in operator new and delete.

We changed our approach into http://codereview.chromium.org/10821125/.


Enable intercepting (de-)allocated types in operator new and delete.
This feature is provided mainly for memory (heap) profiling.

When -fallocated-type-in-operator-new is not specified, it changes nothing.

If
1) -fallocated-type-in-operator-new is specified to Clang, and
2) 'void* operator new(size_t, const type_info&)' is declared in the C++ code,
new expressions are switched to call the declared 'operator new' with an
allocated type given in the second argument.

Similar switching for 'operator delete' and placement 'new's.

Please see
- an example 'AllocatedTypeExample1.cpp', and
- a brief document 'AllocatedType-README.txt'
in this patchset.


TODO: Temporary objects may be leaking?