HP-UX shared libraries do not build any longer, as EX_LIBS contains

HP-UX shared libraries do not build any longer, as EX_LIBS contains
"-Wl,+s" instead of +s:
* Hardcoded necessary references to -ldld/-ldl into the build rules and
  removed EX_LIBS.

HP-UX records the pathnames of dependent libraries when the shared libs
are built, so that ./libcrypto.sl... is recorded in libssl.sl..., with
"./" not being resolvable when running an application linked against -lssl:
* Build libssl without explicit reference to libcrypto, applications will
  be linked with "-lssl -lcrypto" anyway.

Document these informations in Makefile.org.