Add a variable %{ackldflags} so I can pass `-fp`. This change seems
to cause the build to relink every ackprogram, because the link now
needs to use %{ackldflags} even if the flags are empty.
mandelbrot_c_cpm runs in YAZE-AG; startrek_c_cpm doesn't run because
it doesn't fit in the 16-bit address space.
This library is for software floating point. The i80 back end has
never implemented floating point, and might not be ready for libfp.
This commit only builds libfp without using it.
I edit first/build.lua and plat/build.lua to allow `ack -c.s`, then
use FP.script to edit the assembly code. I edit FP.script so it
writes the edited assembly code to stdout, not to the input file.
This needed lots of refactoring to ego --- not all platforms have ego descr
files, and ego will just crash if you invoke it without one. I think originally
it was never intended that these platforms would be used at -O2 or above.
Plats now only specify the ego descr file if they have one.
