Merge commit 0fac1c191 from llvm git (by Craig Topper):

[X86] Allow Yz inline assembly constraint to choose ymm0 or zmm0 when
avx/avx512 are enabled and type is 256 or 512 bits

gcc supports selecting ymm0/zmm0 for the Yz constraint when used with
256 or 512 bit vector types.

Fixes PR45806

Differential Revision: https://reviews.llvm.org/D79448

This should fix 'fatal error: error in backend: Cannot select' errors if
assertions are disabled, or 'Assertion failed: (isVector() && "Invalid
vector type!"), function getVectorNumElements, file
/usr/src/contrib/llvm-project/llvm/include/llvm/CodeGen/ValueTypes.h,
line 276.', when building the audio/lsp-plugins-lv2 port.

Direct commit to stable/{11,12} since head has clang 11.0.0, which
already includes this fix.

Reported by: yuri
PR: 232911