Update llvm-project submodule
Update llvm-project submodule

Bring in rust-lang/llvm-project#24 which brings in some wasm
improvements related to the bulk-memory proposal

aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust