[AIX] Update CMake linker flags to use large glink code

Building clang/llvm as a debug build results in TOC overflow even when
using large code model on AIX. This review updates the
llvm/cmake/modules/HandleLLVMOptions.cmake file to use large glink code
in addition to building as a large code model.

Differential Revision: https://reviews.llvm.org/D151733