MakeSubdirs() macro becomes very unsafe, as it hooks the subdirectories'
build commands to the "all" target, along with main program executable.
If MakeSubdirs() was used to build a dependency of the main program, it
is highly likely that parallel build (-jX) will fail; and that's what's
happening to this port here.
To remedy the problem, use NamedTargetSubdirs() instead; also make sure
that correct make(1) implementation would be used for sub-makes (ignore
bogus "MAKE = make" set by imake in generated Makefiles).
While here, improve wording and formatting in the port description.
Reported by: marino
83b4c7ea73