[llvm] [Gisel][AArch64] legalize G_IS_FPCLASS (PR #72796)

[Amara Emerson via llvm-commits]

aemerson wrote:

> Sorry. How can I update `legalizer-info-validation.mir`? The usual workflow does not work.

You just have to look at the output from the test command and make the test match.

Although to be honest that test doesn't have a lot of value anymore since we use custom predicates at some point in every opcode. We should probably just delete it.

https://github.com/llvm/llvm-project/pull/72796