Auto merge of #40779 - arielb1:bad-arm, r=alexcrichton

update LLVM with fix for PR32379

Fixes #40593.

The "root" codegen bug fixed here is that, when generating ARM code, unpatched LLVM 3.9/3.9.1 miscompiles bit operations in rare circumstances - this can cause user code compiled via LLVM (through both `rustc` and `clang`) to subtly return incorrect results - for more details, see the test in this PR or in the LLVM rare report.

One effect of that LLVM bug is that `rustc` 1.17 (and possibly other versions) is miscompiled on ARM. The code generated by a miscompiled `rustc` lacks destructor calls in many circumstances.

Users who run an affected/miscompiled `rustc` - 1.17 or above - on an ARM build machine will be affected by the (fairly blatant) missing destructor bug, regardless of the target architecture (this includes the official `1.17.0-beta.1`, `1.17.0-beta.2`, and some official 1.17/1.18 nightlies).

Users who use an affected LLVM (that's any unpatched LLVM 3.9/3.9.1), whether through `rustc` (in any version that supports 3.9 - that's 1.12 or above) or through `clang`, who compile code to an ARM target architecture might be affected by the (fairly hard to hit) bit operation bug, regardless of the build machine.

Distributors and user who want to compile rustc using their own LLVM should apply the [patch](https://github.com/llvm-mirror/llvm/commit/cdc303e5ed4d3110e6f70931775a70bb1de44ed6) to avoid miscompilations.

r? @alexcrichton
Beta-nominating because regression (rustc 1.16 is not blatantly miscompiled). This also picks a fix for the (MSVC-affecting) PR29151.