Make mtime omni-parsable

libmtime sometimes used modules with the following syntax:
use :: module_name
unfortunately, the omni-compiler (on which CLAW relies) was unable to parse this. This merge request therefore changes all
use :: module_name to use module_name

src/libmtime.f90

@@ -2936,6 +2936,8 @@ contains
        if (tmp_errno /= 0) then
           deallocate(ret_event)
           ret_event => NULL()
+       ELSE
+          res_errno = tmp_errno
        end if
     end if