compiling 7.4 under MacOS 10.4.6 using ports....

In file included from ../../../../src/include/storage/spin.h:50,
                  from xlog.c:35:
../../../../src/include/storage/s_lock.h:543:2: error: #error
PostgreSQL does not have native spinlock support on this platform. To
continue the compilation, rerun configure using --disable-spinlocks.
However, performance will be poor. Please report this to pgsql-
bugs@postgresql.org.
In file included from ../../../../src/include/storage/spin.h:50,
                  from xlog.c:35:
../../../../src/include/storage/s_lock.h:551: error: conflicting
types for 'slock_t'
../../../../src/include/pg_config_os.h:11: error: previous
declaration of 'slock_t' was here
gnumake[4]: *** [xlog.o] Error 1
gnumake[3]: *** [transam-recursive] Error 2
gnumake[2]: *** [access-recursive] Error 2
gnumake[1]: *** [all] Error 2
gnumake: *** [all] Error 2