Stop providing branch prediction information

The __builtin_expect() can be used to provide the compiler with branch
prediction information.  The Gcc manual says[1] on the subject:

    In general, you should prefer to use actual profile feedback for
    this (-fprofile-arcs), as programmers are notoriously bad at
    predicting how their programs actually perform.

Stop using __builtin_expect() and ISC_LIKELY() and ISC_UNLIKELY() macros
to provide the branch prediction information as the performance testing
shows that named performs better when the __builtin_expect() is not
being used.

1. https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005fexpect

lib/isc/hash.c

@@ -15,7 +15,6 @@
 
 #include "entropy_private.h"
 #include "isc/hash.h" /* IWYU pragma: keep */
-#include "isc/likely.h"
 #include "isc/once.h"
 #include "isc/random.h"
 #include "isc/result.h"
@@ -74,7 +73,7 @@ static uint8_t maptolower[] = {
 
 const void *
 isc_hash_get_initializer(void) {
-	if (ISC_UNLIKELY(!hash_initialized)) {
+	if (!hash_initialized) {
 		RUNTIME_CHECK(
 			isc_once_do(&isc_hash_once, isc_hash_initialize) ==
 			ISC_R_SUCCESS);
@@ -91,7 +90,7 @@ isc_hash_set_initializer(const void *initializer) {
 	 * Ensure that isc_hash_initialize() is not called after
 	 * isc_hash_set_initializer() is called.
 	 */
-	if (ISC_UNLIKELY(!hash_initialized)) {
+	if (!hash_initialized) {
 		RUNTIME_CHECK(
 			isc_once_do(&isc_hash_once, isc_hash_initialize) ==
 			ISC_R_SUCCESS);