debug/108772 - ICE with late debug generated with -flto

debug/108772 - ICE with late debug generated with -flto

When combining -g1 with -flto we run into the DIE location annotation
machinery for globals calling dwarf2out_late_global_decl but not
having any early generated DIE for function scope statics.  In
this process we'd generate a limbo DIE since also the function scope
doesn't have any early generated DIE.  The limbo handling then tries
to force a DIE for the context chain which ultimatively fails and
ICEs at the std namespace decl because at -g1 we don't represent that.

The following avoids this situation by making sure to never generate
any DIEs from dwarf2out_late_global_decl in the in_lto_p path
for function scope globals but rely on DIE generation for
the function to output a DIE for the local static (which doesn't
happen for -g1).

I explored a lot of other options to fix this but in the end this
seems to be the most spot-on fix with the least risk of unwanted
effects.

	PR debug/108772
	* dwarf2out.cc (dwarf2out_late_global_decl): Do not
	generate a DIE for a function scope static.

	* g++.dg/lto/pr108772_0.C: New testcase.