Add support for const operands and options to global_asm!

On x86, the default syntax is also switched to Intel to match asm!

compiler/rustc_ast_lowering/src/lib.rs

@@ -77,6 +77,7 @@ macro_rules! arena_vec {
     });
 }
 
+mod asm;
 mod expr;
 mod item;
 mod pat;