Revert "Reland [CFGuard] Add address-taken IAT tables and delay-load support"

This broke both Firefox and Chromium (PR47905) due to what seems like dllimport
function not being handled correctly.

> This patch adds support for creating Guard Address-Taken IAT Entry Tables (.giats$y sections) in object files, matching the behavior of MSVC. These contain lists of address-taken imported functions, which are used by the linker to create the final GIATS table.
> Additionally, if any DLLs are delay-loaded, the linker must look through the .giats tables and add the respective load thunks of address-taken imports to the GFIDS table, as these are also valid call targets.
>
> Reviewed By: rnk
>
> Differential Revision: https://reviews.llvm.org/D87544

This reverts commit cfd8481d.