Use -Bsymbolic for shared libraries on HP-UX and Solaris.
These platforms are also subject to the mis-linking problem addressed
in commit
e3d77ea6b. It's not clear whether we could solve it with
a solution equivalent to GNU ld's version scripts, but -Bsymbolic
appears to fix it, so let's use that.
Like the previous commit, back-patch as far as v10.
Discussion: https://postgr.es/m/
153626613985.23143.
4743626885618266803@wrigleys.postgresql.org