Use the compiler to find libftdi
Use the compiler to find libftdi

The libfdti detection, using ldconfig, only searches for the build
architecture libftdi, which means infnoise can't be cross-compiled.
By checking whether the compiler knows about the library we can
check for the host architecture's library and support build scenarios
which ldconfig doesn't know about, in particular cross-building.

waywardgeek/infnoise,waywardgeek/infnoise,waywardgeek/infnoise,waywardgeek/infnoise