Old .o files stop working if they use floating point. One must
recompile those files. Old files don't call libfp in the correct way,
and may use symbols that I removed from libem. I don't keep old
symbols in libem/flp.s, because a program that pulls both libfp and
flp.s would get "multiply defined" errors in the linker.
I teach mach/i80/ncg/table to use libfp by copying or adapting the
patterns from mach/i86/ncg/table. I did not test all the patterns,
but I did use `ack -mcpm -fp -O4` to compile examples/mandelbrot.c,
then I ran it in the emulator YAZE-AG. It worked, but it was slow.
This breaks all machines because the declared return type void
disagrees with the implicit return type int (when I compile mach.c
with clang). Unbreak i386, i80, i86, m68020, powerpc, vc4 by adding
the return types to mach.c. We don't build any other machines; they
are broken since commit a46ee91 (May 19, 2013) declared void prolog()
and commit fd91851 (Nov 10, 2016) declared void mes(), with both
declarations in mach/proto/ncg/fillem.c.
Also fix mach/vc4/ncg/mach.c where type full is long, so fprintf()
must use "%ld" not "%d" to print full nlocals.
