Revert "Reland "Switch from GNU to LLVM based tools.""

This reverts commit ed439f26.

Reason for revert: likely culprit of crbug.com/1251776

Original change's description:
> Reland "Switch from GNU to LLVM based tools."
>
> This is a reland of bf16b335
>
> Original change's description:
> > Switch from GNU to LLVM based tools.
> >
> > Android NDK 23 switched to a LLVM based toolchain. However some LLVM
> > based tools like llvm-readobj and llvm-objcopy are available with NDK 22
> > already. To prepare the roll to NDK 23, switch to llvm-readobj and
> > llvm-copy for Android builds.
> >
> > Bug: 1246049
> > Change-Id: I1cc3cec4aeaa159f6189f810ff6e709879b51204
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3162163


> > Reviewed-by: Hans Wennborg <hans@chromium.org>
> > Commit-Queue: Richard Townsend <richard.townsend@arm.com>
> > Cr-Commit-Position: refs/heads/main@{#922566}
>
> Bug: 1246049
> Change-Id: I428f5f8fb19e09e21afd83aec3d9fe80e910b8fe
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3168334


> Reviewed-by: Hans Wennborg <hans@chromium.org>
> Commit-Queue: Richard Townsend <richard.townsend@arm.com>
> Cr-Commit-Position: refs/heads/main@{#923362}

Bug: 1246049, 1251776
Change-Id: Ibffec6380c789c5422340bc9e1a896330d33f2ce
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3174351
Auto-Submit: bttk <bttk@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: bttk <bttk@chromium.org>
Owners-Override: bttk <bttk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#923587}