New -fcatch-undefined-behavior features:

New -fcatch-undefined-behavior features:
 * when checking that a pointer or reference refers to appropriate storage for a type, also check the alignment and perform a null check
 * check that references are bound to appropriate storage
 * check that 'this' has appropriate storage in member accesses and member function calls

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162523 91177308-0d34-0410-b5e6-96231b3b80d8