There's yet more unnecessary semicolons knocking around in the public LLVM headers, which are purely stylistic issues. Just silence them.

`LegacyIRCompileLayer` is now annotated with deprecated, so we need to disable the warning for that too (and move to the new JIT in time).

Bug: b/152339534
Change-Id: Id84fe88fd2f6b50000e37a8b84f52742ca9db646
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/43010Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Ben Clayton <bclayton@google.com>