In order to get cross-platform PMDA installs working, for
PMDAs that have installed makefiles, we need to know about:
how shared libraries are built
shared library suffix
executable suffix
... this is a solved problem in the PCP build, but the PMDA
installed makefiles do not use this. Instead of attempting
to reinvent the wheel one platform at a time, just make use
of the already installed $PCP_INC_DIR/build{rules,defs}.
In order to get cross-platform PMDA installs working, for
PMDAs that have installed makefiles, we need to know about: