libutils: T* is a trivial type

Avoid calling constructors/destructors for
each element, when we have Vector<T*>. These
are used in libbinder and elsewhere.

std::vector is still faster but uses more mem.

Bugs: me
Test: boot && binderLibTest
Change-Id: Id1239daddd018f8eee5480d1cb6dd25d6f4df808