duration-subsec: make lint adhere to lint message convention

Author: matthiaskrgr

clippy_lints/src/duration_subsec.rs

@@ -56,7 +56,7 @@ impl<'tcx> LateLintPass<'tcx> for DurationSubsec {
                     cx,
                     DURATION_SUBSEC,
                     expr.span,
-                    &format!("Calling `{}()` is more concise than this calculation", suggested_fn),
+                    &format!("calling `{}()` is more concise than this calculation", suggested_fn),
                     "try",
                     format!(
                         "{}.{}()",

tests/ui/duration_subsec.stderr

@@ -1,30 +1,30 @@
-error: Calling `subsec_millis()` is more concise than this calculation
+error: calling `subsec_millis()` is more concise than this calculation
   --> $DIR/duration_subsec.rs:10:24
    |
 LL |     let bad_millis_1 = dur.subsec_micros() / 1_000;
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `dur.subsec_millis()`
    |
    = note: `-D clippy::duration-subsec` implied by `-D warnings`
 
-error: Calling `subsec_millis()` is more concise than this calculation
+error: calling `subsec_millis()` is more concise than this calculation
   --> $DIR/duration_subsec.rs:11:24
    |
 LL |     let bad_millis_2 = dur.subsec_nanos() / 1_000_000;
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `dur.subsec_millis()`
 
-error: Calling `subsec_micros()` is more concise than this calculation
+error: calling `subsec_micros()` is more concise than this calculation
   --> $DIR/duration_subsec.rs:16:22
    |
 LL |     let bad_micros = dur.subsec_nanos() / 1_000;
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `dur.subsec_micros()`
 
-error: Calling `subsec_micros()` is more concise than this calculation
+error: calling `subsec_micros()` is more concise than this calculation
   --> $DIR/duration_subsec.rs:21:13
    |
 LL |     let _ = (&dur).subsec_nanos() / 1_000;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(&dur).subsec_micros()`
 
-error: Calling `subsec_micros()` is more concise than this calculation
+error: calling `subsec_micros()` is more concise than this calculation
   --> $DIR/duration_subsec.rs:25:13
    |
 LL |     let _ = dur.subsec_nanos() / NANOS_IN_MICRO;