[clang] Ensure that statements, expressions and types are trivially destructible

Since statements, expressions and types are allocated with the BumpPtrAllocator
from ASTContext their destructor is not executed. Two classes are currently
exempted from the check : InitListExpr due to its ASTVector and
ConstantArrayType due to its APInt.

No functional changes.

Differential Revision: https://reviews.llvm.org/D66646

Reviewed By: lebedev.ri, gribozavr

llvm-svn: 370044