[fink-core] MaxCores in fink.conf and make -j

[monipol <mo...@gm...>]

Hello, all. What do you think of having a MaxCores parameter in  
fink.conf and a %-field that could be explicitly used by maintainers  
as in

SetMAKEFLAGS: -j%{MaxCores}

or something similar? In this way maintainers that have tested their  
packages with -j could use that information without resorting to  
`sysctl hw.ncpu` *and* users would be able to define their preferred  
value in case they don't want all the cores to be used.

Also, Daniel Macks suggested having a MaxCores .info field, defaulting  
to false, that could be set to true by packagers willing to use -j  
with MaxCores. Quoting him: 'Seems like such a special-purpose %exp  
that would only be used in one context, no need to pollute the whole  
%exp table for every field parsing. For the corner-case where need to  
pass -jX some way other than MAKEFLAGS env var, could just use the env  
var in the *Script directly.'

Bootstrap and fink configure could be modified to ask users which  
value of MaxCores they prefer, showing the value of `sysctl hw.cpu` at  
the prompt but not restricting whatever the user inputs to be less  
than or equal to `sysctl hw.cpu`. Peter O'Gorman reports that -j3 is  
faster than -j2 on his dual core machine.


Cheers,

-- monipol