The config check of the results of testing for dlfcn.h or dl.h just tests the
value of the ac_cv_ variables, which will be 'yes' or 'no', rather than checking
it is 'yes', so loadable module support would always be detected.

This is necessary for successful compilation for the MinGW target without the
optional dlfcn-win32 library.

v2: Also, fixed typoed name of ac_cv_header_dlfcn_h, so check still works
correctly when dlfcn.h is available

Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Reviewed-by: Dan Nicholson <dbn.lists@gmail.com>