CLEANUP: errors: fix obsolete function comments

Since 9f903af5 ("MEDIUM: log: slightly refine the output format of
alerts/warnings/etc"), messages generated by ha_{alert,warning,notice}
don't embed date/time information anymore.

Updating some old function comments that kept saying otherwise.
diff --git a/src/errors.c b/src/errors.c
index ba4b8ce..da10c2f 100644
--- a/src/errors.c
+++ b/src/errors.c
@@ -419,7 +419,7 @@
 }
 
 /*
- * Displays the message on stderr with the date and pid. Overrides the quiet
+ * Displays the message on stderr with the pid. Overrides the quiet
  * mode during startup.
  */
 void ha_alert(const char *fmt, ...)
@@ -443,7 +443,7 @@
 }
 
 /*
- * Displays the message on stderr with the date and pid.
+ * Displays the message on stderr with the pid.
  */
 void ha_warning(const char *fmt, ...)
 {
@@ -504,7 +504,7 @@
 }
 
 /*
- * Displays the message on stderr with the date and pid.
+ * Displays the message on stderr with the pid.
  */
 void ha_notice(const char *fmt, ...)
 {