Fix linking problem on Solaris 10.

libcfexecd.a is empty on non-Windows platforms, and Solaris doesn't
like that.
fixes bug #3408 aix getprocs64 already defined on aix 6.1
fix typo in previous commit
add comment
Merge pull request #990 from McAtte/3.5.x-fix-getprocs64-aix

3.5.x fix getprocs64 aix
Fix redmine #2936

(cherry picked from commit 10e13854842df6c9356421c9de6fa9103559c163)

Include changelog update.