debug-early branch merged into mainline

[Aldy Hernandez]

The debug-early work has been merged into mainline.

There is a known Ada failure which Eric B. knows about and approved, and 
for which there is an appropriate FIXME note in the Ada sources:

+FAIL: gnat.dg/specs/debug1.ads scan-assembler-times DW_AT_artificial 17

There is also a known regression in the testsuite that we've discussed 
before and will be fixed shortly.  It is an optimization issue:

+FAIL: gcc.dg/debug/dwarf2/stacked-qualified-types-3.c 
scan-assembler-times DIE \\([^\n]*\\) 
DW_TAG_(?:const|volatile|atomic|restrict)_type 8

Finally, as previously discussed there can be substantial increases in 
the size of the .debug_info sections for a minimum of cases.  This is 
immediately on my plate as of right now.  It is expected.  Please don't 
report this, or any of the above 2 failures.

Thanks to everyone involved in the design and review, particularly Jason 
and Richi who were there at each step of the way, and Michael Matz whose 
original patch this work is based off of.

Aldy