cmake: gr-dtv: fix internal GR component dependencies
cmake: FindUHD: add in checks to see whether UHDConfig*.cmake were used via the ENV variables; CACHE variables are unreliable from withing UHDConfig*.cmake for some reason.  In the case where UHDConfig*.cmake were used, do not do checking for UHD here.  Print out appropriate errors if REQUIRED is set.
cmake: OSS is not for APPLE or WINDOWS.
cmake: Use APPLE, not matching Darwin
cmake: modtool: allow the use of a MODULES_DIR to specify where cmake modules are installed.
cmake: modtool: On Apple only, set install name and use rpath correctly.
cmake: modtool: make sure our local CMake Modules path comes first.
cmake: modtool: update copyright date.
Merge branch 'maint'
cmake: modtool: update Modules to GR master