JITLink: Add missing EHFrame NULL terminator on aarch64/ELF

This fixes test failures on AArch64 with libgcc-13:

Clang :: Interpreter/global-dtor.cpp
Clang-Unit :: Interpreter/./ClangReplInterpreterTests/2/4

Reviewed By: lhames, v.g.vassilev

Differential Revision: https://reviews.llvm.org/D146067