(setting CMAKE_PREFIX_PATH should not be required) should just work, but it is
always possible (although I haven't checked documentation to see) there is
some incorrect syntax in that line so I would also use message to print
out the PKG_CONFIG_PATH environment variable to see what you have actually
set it to within CMake.
Alan W. Irwin
Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).