don't configure anything out if the feature is not enabled

Author: folkertdev

compiler/rustc_builtin_macros/src/asm.rs

@@ -168,7 +168,8 @@ pub fn parse_asm_args<'a>(
         } // accept trailing commas
 
         let attributes = AsmAttrVec::parse(ecx, p)?;
-        let is_configured_out = strip_unconfigured.configure(attributes).is_none();
+        let is_configured_out =
+            ecx.ecfg.features.asm_cfg() && strip_unconfigured.configure(attributes).is_none();
 
         // Parse clobber_abi
         if p.eat_keyword(exp!(ClobberAbi)) {