rustc: Fix typo in error message

src/rustc/driver/rustc.rs

@@ -93,7 +93,7 @@ fn run_compiler(args: [str], demitter: diagnostic::emitter) {
         ret;
     }
     let ifile = alt vec::len(match.free) {
-      0u { early_error(demitter, "o input filename given") }
+      0u { early_error(demitter, "no input filename given") }
       1u { match.free[0] }
       _ { early_error(demitter, "multiple input filenames provided") }
     };