It's unclear why this option would be necessary, and it causes problems
when people do not match it to their toolchain and CFLAGS.
To set the float abi, either use a toolchain with an appropriate default
or set the float-abi option in the CFLAGS environment variable.
This should resolve#2586.
Recent cmake versions (starting with 3.0) don't use multiarch
libdir when the install prefix is not /usr. To have the same library
directory for all packages explicitly set CMAKE_INSTALL_LIBDIR to lib.
