Dwarf2 failure with Ada

[Richard Kenner]

This showed up this morning on a run from the 3.1 branch:

../../xgcc -B../../ -c -O2  -gnatpgn -g -I. -I.. -I/bonn.a/gnatmail-5/build-bonn/src/gcc/ada \
      s-tasdeb.adb -o s-tasdeb.o
+===========================GNAT BUG DETECTED==============================+
| 5.00w (20020226) (i686-pc-linux-gnu) GCC error:                          |
| Internal compiler error in add_abstract_origin_attribute, at             |
|    dwarf2out.c:9427                                                      |