[HLSL] Remove global ctor/dtor variable for non-lib profile.

After generated call for ctor/dtor for entry, global variable for ctor/dtor are useless.
Remove them for non-lib profiles.
Lib profile still need these in case export function used the global variable which require ctor/dtor.

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D133993