CMAKE_<LANG>_COMPILER_EXTERNAL_TOOLCHAINΒΆ
The external toolchain for cross-compiling, if supported.
Some compiler toolchains do not ship their own auxiliary utilities such as
archivers and linkers. The compiler driver may support a command-line argument
to specify the location of such tools.
CMAKE_<LANG>_COMPILER_EXTERNAL_TOOLCHAIN
may be set to a path to
the external toolchain and will be passed to the compiler driver if supported.
This variable may only be set in a toolchain file specified by
the CMAKE_TOOLCHAIN_FILE
variable.