Path to pass to the compiler in the --sysroot flag.

The CMAKE_SYSROOT content is passed to the compiler in the --sysroot flag, if supported. The path is also stripped from the RPATH/RUNPATH if necessary on installation. The CMAKE_SYSROOT is also used to prefix paths searched by the find_* commands.

This variable may only be set in a toolchain file specified by the CMAKE_TOOLCHAIN_FILE variable.