[UBSan] Strengthen pointer checks in 'new' expressions

With this change compiler generates alignment checks for wider range
of types. Previously such checks were generated only for the record types
with non-trivial default constructor. So the types like:

    struct alignas(32) S2 { int x; };
    typedef __attribute__((ext_vector_type(2), aligned(32))) float float32x2_t;

did not get checks when allocated by 'new' expression.

This change also optimizes the checks generated for the arrays created
in 'new' expressions. Previously the check was generated for each
invocation of type constructor. Now the check is generated only once
for entire array.

Differential Revision: https://reviews.llvm.org/D49589

llvm-svn: 338199