[Serusers] error compiling ser 0.8.11 on Solaris 2.8 using gcc 3.3

We are trying to compile ser 0.8.11 on Solaris 2.8 using gcc 3.3. Since we don't have librt.so on our system, we change the Makefile.defs to use libpthread instead, we also added "<sched.h>" to be inclueded in the main.c file. However, during the compilation, we still got the error message: Extra objs: gcc -O2 action.o crc.o data_lump.o data_lump_rpl.o dprint.o dset.o error.o fifo_server.o flags.o forward.o hash_func.o ip_addr.o main.o md5.o md5utils.o modparam.o msg_translator.o pass_fd.o proxy.o receive.o resolve.o route.o route_struct.o script_cb.o sr_module.o stats.o tcp_main.o tcp_read.o timer.o udp_server.o mem/f_malloc.o mem/mem.o mem/memtest.o mem/q_malloc.o mem/shm_mem.o mem/vq_malloc.o parser/hf.o parser/msg_parser.o parser/parse_content.o parser/parse_cseq.o parser/parse_event.o parser/parse_expires.o parser/parse_fline.o parser/parse_from.o parser/parse_hname2.o parser/parse_hostport.o parser/parse_nameaddr.o parser/parse_param.o parser/parse_rr.o parser/parse_to.o parser/parse_uri.o parser/parse_via.o parser/parser_f.o parser/digest/digest.o parser/digest/digest_parser.o parser/digest/param_parser.o parser/contact/contact.o parser/contact/parse_contact.o db/db.o lex.yy.o cfg.tab.o -lfl -ldl -lresolv -L/usr/local/lib -lfl -lxnet -lpthread -lnsl -o ser Undefined first referenced symbol in file sched_yield main.o ld: fatal: Symbol referencing errors. No output written to ser collect2: ld returned 1 exit status make: *** [ser] Error 1 Do we really need librt.so? Which GNU package does that come from? Are there anyone who successfully install ser 0.8.11 on Solaris? Thanks very much. Ziying Sherwin