classes/cmake: CMAKE_RANLIB needs to be a filename without arguments

classes/cmake: CMAKE_RANLIB needs to be a filename without arguments

CMAKE_RANLIB is the path to the binary without any arguments. However,
gcc-native.bbclass sets BUILD_RANLIB to "ranlib -D" which means that
CMake looks for a binary called "ranlib;-D".

This is expected behaviour upstream[1] and as there's no variable for
"ranlib flags", we should just set CMAKE_RANLIB to the first element of
the list.

[1] https://gitlab.kitware.com/cmake/cmake/-/issues/23554

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>