Revert "[llvm_tools] automatically uprevs sys-devel/gcc whenever LLVM_NEXT is changed"

This reverts commit a5725194cabd4244fd04c106c3a8d8b0d246b751.

Reason for revert: breaks llvm-next testing. b/194493350

Original change's description:
> [llvm_tools] automatically uprevs sys-devel/gcc whenever LLVM_NEXT is changed
>
> BUG=b:192996912
> TEST=update_chromeos_llvm_hash_unittest.py verified via CQ
>
> Change-Id: Id06f054fdc4400c9b9af48c5383172192cb9a8a3
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3021576
> Tested-by: Christopher Di Bella <cjdb@google.com>
> Auto-Submit: Christopher Di Bella <cjdb@google.com>
> Reviewed-by: Luis Lozano <llozano@chromium.org>
> Commit-Queue: Christopher Di Bella <cjdb@google.com>

Bug: b:192996912, b:194493350
Change-Id: I3a8e70bc20f09d92d594c1821b90157b6b5aba18
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3048754
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
1 file changed