`-(::BFloat16)` causes LLVM error on Apple M4

[AntonOresten]

On an M4 MacBook running Julia 1.12 I encounter this error, specifically when negating a BFloat16 number:

julia> -one(BFloat16)
LLVM ERROR: Cannot select: 0x11387b570: bf16 = fneg 0x11387af50, int.jl:379 @[ ~/.julia/packages/BFloat16s/BmABx/src/bfloat16.jl:248 ]
  0x11387af50: bf16,ch = CopyFromReg 0x10671b110, Register:bf16 %1
    0x11387aee0: bf16 = Register %1
In function: julia_-_2881

[45869] signal 6: Abort trap: 6
in expression starting at REPL[4]:1
__pthread_kill at /usr/lib/system/libsystem_kernel.dylib (unknown line)
Allocations: 14871363 (Pool: 14869443; Big: 1920); GC: 17
zsh: abort      julia +1.12

The error does not happen on my Linux machine:

julia> -one(BFloat16)
BFloat16(-1.0)