4811. [bug] Revert api changes to use <isc/buffer.h> inline

macros.  Provide a alternative mechanism to turn
                        on the use of inline macros when building BIND.
                        [RT #46520]

config.h.in

@@ -535,6 +535,9 @@ int sigwait(const unsigned int *set, int *sig);
 /* Define to the sockaddr length type used by getnameinfo(3). */
 #undef IRS_GETNAMEINFO_SOCKLEN_T
 
+/* Define if you want to use inline buffers */
+#undef ISC_BUFFER_USEINLINE
+
 /* Define to allow building of objects for dlopen(). */
 #undef ISC_DLZ_DLOPEN