Added support for DAKOTA_DL_SOLVER, defaulted to off. If DAKOTA_DL_SOLVER is requested in the CMake build, a probe for dlfcn.h is invoked and the configuration is allowed IF dlfcn.h is found.
Added support for DAKOTA_DL_SOLVER, defaulted to off.
If DAKOTA_DL_SOLVER is requested in the CMake build, a probe for
dlfcn.h is invoked and the configuration is allowed IF dlfcn.h is found.

ToDo:  Test behavior on cygwin.
Partial support for Trac ticket #4158.



git-svn-id: c6750f7dd89925e309f580f56430152d063ff36c@979 aa0779c3-6ec2-4b84-a212-a405c134cd8d

pemryan/DAKOTA,pemryan/DAKOTA,pemryan/DAKOTA,pemryan/DAKOTA,pemryan/DAKOTA,pemryan/DAKOTA,pemryan/DAKOTA