[XRay][compiler-rt] Avoid InternalAlloc(...) in Profiling Mode

Summary:
We avoid using dynamic memory allocated with the internal allocator in
the profile collection service used by profiling mode. We use aligned
storage for globals and in-struct storage of objects we dynamically
initialize.

We also remove the dependency on `Vector<...>` which also internally
uses the dynamic allocator in sanitizer_common (InternalAlloc) in favour
of the XRay allocator and segmented array implementation.

This change addresses llvm.org/PR38577.

Reviewers: eizan

Reviewed By: eizan

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D50782

llvm-svn: 339978