runtime/internal/clite/syscall: fix init

runtime/internal/clite/syscall/syscall_wasm.go

@@ -5,7 +5,6 @@
 package syscall
 
 import (
-	"strconv"
 	"unsafe"
 )
 
@@ -79,7 +78,7 @@ func (e Errno) Error() string {
 			return s
 		}
 	}
-	return "errno " + strconv.Itoa(int(e))
+	return "errno " + utoa(uint64(e))
 }
 
 func (e Errno) Is(target error) bool {
@@ -209,7 +208,7 @@ func (s Signal) String() string {
 	case SIGSYS:
 		return "bad system call"
 	default:
-		return "signal " + strconv.Itoa(int(s))
+		return "signal " + utoa(uint64(s))
 	}
 }