Ada HEAD bootstrap ICE during gnatlib-shared on x86 and x86_64

[Laurent GUERBY]

Bootstrap did work for me last time I tried two days ago.

Laurent

    ../../xgcc -B../../ -c -g -O2 -fPIC      -W -Wall -gnatpg  s-stratt.adb -o s-stratt.o
    +===========================GNAT BUG DETECTED==============================+
    | 4.0.0 20041124 (experimental) (i686-pc-linux-gnu) GCC error:             |
    | in gen_lowpart_general, at rtlhooks.c:58                                 |
    | Error detected at s-stratt.adb:671:1                                     |