It would help if you pasted the libtool line as well; FYI, my system
produces

rm -f libpcre.la
/bin/sh ./libtool --mode=link --tag=CC cc -export-symbols-regex '^[^_]' -Wl,-R/usr/pkg/lib -I. -I. -rpath /usr/pkg/lib -version-info  '0:1:0' -o libpcre.la pcre_chartables.lo  pcre_compile.lo  pcre_config.lo  pcre_dfa_exec.lo  pcre_exec.lo  pcre_fullinfo.lo  pcre_get.lo  pcre_globals.lo  pcre_info.lo  pcre_maketables.lo  pcre_ord2utf8.lo  pcre_refcount.lo  pcre_study.lo  pcre_tables.lo  pcre_try_flipped.lo  pcre_ucp_searchfuncs.lo  pcre_valid_utf8.lo  pcre_version.lo  pcre_xclass.lo
generating symbol list for `libpcre.la'
nm  .libs/pcre_chartables.o .libs/pcre_compile.o .libs/pcre_config.o .libs/pcre_dfa_exec.o .libs/pcre_exec.o .libs/pcre_fullinfo.o .libs/pcre_get.o .libs/pcre_globals.o .libs/pcre_info.o .libs/pcre_maketables.o .libs/pcre_ord2utf8.o .libs/pcre_refcount.o .libs/pcre_study.o .libs/pcre_tables.o .libs/pcre_try_flipped.o .libs/pcre_ucp_searchfuncs.o .libs/pcre_valid_utf8.o .libs/pcre_version.o .libs/pcre_xclass.o  | sed -n -e 's/^.*[       ]\([ABCDGIRSTW][ABCDGIRSTW]*\)[         ][      ]*\([_A-Za-z][_A-Za-z0-9]*\)$/\1 \2 \2/p' | /usr/bin/sed 's/.* //' | sort | uniq > .libs/libpcre.exp

And so the missing command between "|  |" is a big awful sed expression.