Pre-load a script to populate the cache.
When cmake is first run in an empty build tree, it creates a CMakeCache.txt file and populates it
with customizable settings for the project. This option may be used to specify a file from which
to load cache entries before the first pass through the project's cmake listfiles. The loaded
entries take priority over the project's default values. The given file should be a CMake script
containing SET commands that use the CACHE option, not a cache-format file.