[RuntimeDyld] Fix debug section relocation (pr20457)

Summary:
Debug info sections, (or non-SHF_ALLOC sections in general) should be
linked as if their load address was zero to emulate the behavior of the
static linker.

This bug was discovered because it was breaking lldb expression evaluation on
linux.

Reviewers: lhames

Subscribers: aprantl, eugene, clayborg, lldb-commits, llvm-commits

Differential Revision: https://reviews.llvm.org/D32899

llvm-svn: 303239