erthink-cmake: fix/enable LTO-detection for Clang >= 7.0 with CMAKE_TOOLCHAIN_FILE.
erthink-cmake: fix/enable LTO-detection for Clang >= 7.0 with CMAKE_TOOLCHAIN_FILE.

leo-yuriev/libfpta,leo-yuriev/libfpta,leo-yuriev/libfptu,leo-yuriev/libfptu