liblthread conflicts on HP-UX 10.20

[Jonathan B Ellis <ellis@et.byu.edu>]

liblthread is conflicting with libpthreads in slapd:

make[2]: Entering directory `/tmp_mnt/auto/src/ldap/servers/slapd'
/bin/sh /tmp_mnt/auto/src/ldap/libtool --mode=link /usr/local/pthreads/bin/pgcc -g -O2 -I../../include -I../../include   -DHAVE_CONFIG_H     -o slapd main.o daemon.o connection.o search.o filter.o add.o charray.o attr.o entry.o config.o backend.o result.o operation.o dn.o compare.o modify.o delete.o modrdn.o ch_malloc.o value.o ava.o bind.o unbind.o abandon.o filterentry.o phonetic.o acl.o str2filter.o aclparse.o init.o repl.o lock.o suffixalias.o schema.o schemaparse.o monitor.o configinfo.o version.o -L/tmp_mnt/auto/src/ldap/libraries -lldif /tmp_mnt/auto/src/ldap/libraries/libldap/libldap.la /tmp_mnt/auto/src/ldap/libraries/liblber/liblber.la libbackends.a -lavl -lldbm  -lgdbm -llthread  -llutil  -lV3 
/usr/local/pthreads/bin/pgcc -g -O2 -I../../include -I../../include -DHAVE_CONFIG_H -o slapd main.o daemon.o connection.o search.o filter.o add.o charray.o attr.o entry.o config.o backend.o result.o operation.o dn.o compare.o modify.o delete.o modrdn.o ch_malloc.o value.o ava.o bind.o unbind.o abandon.o filterentry.o phonetic.o acl.o str2filter.o aclparse.o init.o repl.o lock.o suffixalias.o schema.o schemaparse.o monitor.o configinfo.o version.o -L/tmp_mnt/auto/src/ldap/libraries -lldif /tmp_mnt/auto/src/ldap/libraries/libldap/.libs/libldap.a /tmp_mnt/auto/src/ldap/libraries/liblber/.libs/liblber.a libbackends.a -lavl -lldbm -lgdbm -llthread -llutil -lV3
collect2: ld returned 1 exit status
/bin/ld: Duplicate symbol "pthread_yield" in files /tmp_mnt/auto/src/ldap/libraries/liblthread.a(thread.o) and /usr/local/pthreads/lib/libpthread.a(pthread.o)
/bin/ld: Duplicate symbol "pthread_exit" in files /tmp_mnt/auto/src/ldap/libraries/liblthread.a(thread.o) and /usr/local/pthreads/lib/libpthread.a(pthread.o)
/bin/ld: Duplicate symbol "pthread_create" in files /tmp_mnt/auto/src/ldap/libraries/liblthread.a(thread.o) and /usr/local/pthreads/lib/libpthread.a(pthread.o)
/bin/ld: Unsatisfied symbols:
   ldbm_store (code)
   ldbm_sync (code)
   ldbm_fetch (code)
   ldbm_open (code)
   ldbm_datum_free (code)
   ldbm_delete (code)
   ldbm_close (code)
/bin/ld: Found 3 duplicate symbol(s)

(That it can't find the libldbm is another problem.)

I had this conflict with slurpd and removing -llthread from XLIBS fixed it,
but apparently slapd actually uses liblthread.  (Go figure. :)

Incidently, slapd/lock.c includes <ac/unistd.h>, which doesn't define
the macros F_LOCK and F_ULOCK.  I copied those manually from <sys/unistd.h>.

-Jonathan