[Ada] multilib patch take two => multilib build working

[Paolo Bonzini]

Arnaud Charlet wrote:
>>>>>> The idea currently is to make these values
>>>>>> explicit so that when people read system.ads, they know right away what
>>>>>> the right value is.
>> That's "when people read system.ads", not "when people read 
>> system-linux-x86.ads".  In other words, he's not necessarily against 
>> automatically generating system.ads from other means, for example using 
>> configure tests.  Which, I repeat, comes out naturally if the RTS build is 
>> confined in libada.
> 
> Right, that's one possibility, although people seem to be focusing
> in system.ads alot, which is actually only the tip of the iceberg, and not
> a real issue per se.

Still it's the biggest problem so far.

For example, g-bytswa-x86.adb vs. g-bytswa.adb is also a problem because 
a -mcpu=i386 multilib should use the latter; however, that's arguably 
already a GNAT bug for the i386-pc-linux-gnu configuration, so it can be 
left for later.

Good to hear about soccon, though.

Paolo