[Bug modula2/108182] gm2 driver mishandles target and multilib options

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108182

Iain Sandoe <iains at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #54220|0                           |1
        is obsolete|                            |
  Attachment #54248|0                           |1
        is obsolete|                            |

--- Comment #14 from Iain Sandoe <iains at gcc dot gnu.org> ---
Created attachment 54261
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54261&action=edit
Updated patch that honours the order of include use.

This is V5 ...

... so here we collect the incoming search paths and then apply (most of) the
rules in 
https://gcc.gnu.org/onlinedocs/gcc/Directory-Options.html#Directory-Options

... TODO:
 - eliminate duplicate -I entries that have a system one
 - figure out the right way to implement -nostdinc 
 - handle -idirafter