Fix build on FreeBSD
Fix build on FreeBSD

Add the ELF symbol name to the exported symbol list. bfd exports
all symbols if it can't find any symbols in the export list. lld
(the FreeBSD default linker) exports nothing.

jcsjcs/pg_query,jcsjcs/pg_query,lfittl/pg_query,jcsjcs/pg_query,lfittl/pg_query