Capture underlying type for unsafe/unaligned pointers in ClassFileParser

As part of JDK-8180032 I fixed a problem where ClassFileParser passed around potentially unaligned pointers to various class file data structures, and in some cases dereferenced those unaligned pointers which is not valid in C++. As part of the fix I chose to switch from using typed pointers (like u2*) in favor of void*, to signal that the pointer is not (necessarily) possible to dereference directly. However, by switching to void* the information about the underlying type (u2) is lost, which is unfortunate. The information about the type should be maintained in some way.