Commit 62a4aab9

 set the CMake property LINK_INTERFACE_LIBRARIES to empty
for libwaffle, because Debian's packaging tools complained otherwise.
Afterwards, Waffle's CMake neglected to declare the Cocoa library
dependencies for the executables wflinfo, gl_basic, gl_basic_test.
Post-commit, the executables were no longer satisying their Cocoa
dependency transitively through libwaffle.

Fix the build by linking *every* Waffle target to the Cocoa libraries
with a toplevel `link_libraries` directive.

Also, don't unset LINK_INTERFACE_LIBRARIES on the Mac. It causes a CMake
warning that I don't understand.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>