[PATCH] Support for address space casting in order to map these on the new 'addrspacecast' IR instruction

[Michele Scandale]

  I discover some failures in 'test/SemaCXX/address-space-conversion.cpp' about missing expected errors: in this test were checked errors reported on static upcast and downcast of a pointer to a struct type in different address spaces.

  The expected error should be triggered because the two pointees do not have the same qualifiers, but the patch will still allow the conversion because as last chance to have a static_cast it checks if boh source and destination types are pointers with pointees in different address spaces.

  Would it be semantically correct now to have a static upcast/downcast of pointers/references to struct/classes in different address spaces?

http://llvm-reviews.chandlerc.com/D2241