Ignore LLVM ABI in dlltool tests since those targets don't use dlltool

Author: mati865

src/tools/compiletest/src/header.rs

@@ -820,6 +820,7 @@ const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     "ignore-watchos",
     "ignore-windows",
     "ignore-windows-gnu",
+    "ignore-llvm",
     "ignore-x32",
     "ignore-x86",
     "ignore-x86_64",

tests/ui/rfcs/rfc-2627-raw-dylib/dlltool-failed.rs

@@ -2,6 +2,7 @@
 
 //@ only-gnu
 //@ only-windows
+//@ ignore-llvm
 //@ needs-dlltool
 //@ compile-flags: --crate-type lib --emit link
 //@ normalize-stderr-test: "[^ ']*/dlltool.exe" -> "$$DLLTOOL"

tests/ui/rfcs/rfc-2627-raw-dylib/invalid-dlltool.rs

@@ -2,6 +2,7 @@
 
 //@ only-gnu
 //@ only-windows
+//@ ignore-llvm
 //@ compile-flags: --crate-type lib --emit link -Cdlltool=does_not_exit.exe
 #[link(name = "foo", kind = "raw-dylib")]
 extern "C" {