CMake doesn't detect changed environment variables when reloading project

[rcabell]

Regenerating build directory from an existing project doesn't detect changed environment variables correctly.

Expected Behavior

Calling cmake <path_to_NDHMS> in an existing build directory should detect changed environment variables, including WRF-Hydro options and compilers / MPI libraries

Current Behavior

Only changes to the path to netCDF are detected

Possible Solution

Update CMakeLists.txt to detect these changes similarly to how FindNetCDF.cmake handles them

[hellkite500]

https://cmake.org/pipermail/cmake/2018-May/067501.html

Clearing (deleting) the CMakeCache.txt file before regenerating would probably do the trick as well.