Testcase for bug 17844

[Eric Botcazou]

> I find the prNNNNN format extremely descriptive and helpful.

I personally think it's a step backwards from truly descriptive filenames, 
which have been more or less the rule for gcc.dg so far, e.g.:

-rw-rw-r--    1 eric     eric         1013 Dec 18  2003 bitfld-1.c
-rw-r--r--    1 eric     eric          583 Jul 10 08:19 bitfld-2.c
-rw-rw-r--    1 eric     eric          912 Aug  8  2002 bitfld-3.c
-rw-rw-r--    1 eric     eric          967 Aug 10  2002 bitfld-4.c
-rw-rw-r--    1 eric     eric          259 Nov 20  2002 bitfld-5.c
-rw-rw-r--    1 eric     eric          403 Nov 27  2002 bitfld-6.c
-rw-rw-r--    1 eric     eric          256 Nov 29  2003 bitfld-7.c
-rw-rw-r--    1 eric     eric          333 Dec 17  2003 bitfld-8.c
-rw-rw-r--    1 eric     eric         2927 Sep 11 01:10 bitfld-9.c

And given that the PR number is supposed to be mentioned in the testcase too, 
it's a loss of information.

-- 
Eric Botcazou