CMake debug find

CMake --debug-find option gives extensive human-readable trace output for where the CMake find_* operations are looking for files. In most CMake projects, there are many find_* operations, and so the cmake --debug-find output can be overwhelming to scroll through. A more controlled debug-find is available by targeting only specific find_* calls via CMAKE_FIND_DEBUG_MODE.

This example supposes the dev wishes to debug only the finding of LAPACK:

# arbitrary other packages that are not of interest to trace finding
find_package(Git)

# package that's not working right, to debug
set(CMAKE_FIND_DEBUG_MODE on)
find_package(LAPACK)
set(CMAKE_FIND_DEBUG_MODE off)