CMake variables FLTK_SOURCE_DIR and FLTK_BINARY_DIR are only defined
if the project name is exactly "FLTK" (all uppercase). These variables
are generated (set) by CMake as <PROJECT_NAME>_SOURCE_DIR etc.
The correct variables are CMAKE_SOURCE_DIR and CMAKE_BINARY_DIR,
respectively, which are always defined.
This commit enables future changes of the FLTK project name, e.g. to
"fltk" or "fltk-1.4.0" (a versioned project name), if we like...
git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12281 ea41ed52-d2ee-0310-a9c1-e6b18d33e121