Refactor isc_time_now() to return time, and not result

The isc_time_now() and isc_time_now_hires() were used inconsistently
through the code - either with status check, or without status check,
or via TIME_NOW() macro with RUNTIME_CHECK() on failure.

Refactor the isc_time_now() and isc_time_now_hires() to always fail when
getting current time has failed, and return the isc_time_t value as
return value instead of passing the pointer to result in the argument.

lib/isc/include/isc/time.h

@@ -166,8 +166,8 @@ isc_time_monotonic(void);
  * Returns the system's monotonic time in linear nanoseconds.
  */
 
-isc_result_t
-isc_time_now(isc_time_t *t);
+isc_time_t
+isc_time_now(void);
 /*%<
  * Set 't' to the current absolute time.
  *
@@ -185,8 +185,8 @@ isc_time_now(isc_time_t *t);
  *		in the current definition of isc_time_t.
  */
 
-isc_result_t
-isc_time_now_hires(isc_time_t *t);
+isc_time_t
+isc_time_now_hires(void);
 /*%<
  * Set 't' to the current absolute time. Uses higher resolution clocks
  * recommended when microsecond accuracy is required.

lib/isc/include/isc/util.h

@@ -357,13 +357,6 @@ mock_assert(const int result, const char *const expression,
 		FATAL_SYSERROR(ret, "%s()", #func); \
 	}
 
-/*%
- * Time
- */
-#define TIME_NOW(tp) RUNTIME_CHECK(isc_time_now((tp)) == ISC_R_SUCCESS)
-#define TIME_NOW_HIRES(tp) \
-	RUNTIME_CHECK(isc_time_now_hires((tp)) == ISC_R_SUCCESS)
-
 /*%
  * Alignment
  */