ada/6558: [mainline regression] Wrongly reverted patches

[Nathanael Nerode]

Found the first bogus reversion, from ChangeLog 1.105 by neil.

ada:	* misc.c (gnat_decode_option, gnat_init_options): Make definitions
	static too.
	(gnat_init): Don't return NULL.
	
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6558

So the ChangeLog only has to be checked from here to Geert's fatal patch 
at 1.201.  I can and will do this; I'd like someone else to help me by 
unreverting the patches as I find them.  I think we can get this done 
pretty efficiently, actually.

--Nathanael