[PATCH] Fix libstdc++ tests requiring atomic support on hppa-hpux

[Hans-Peter Nilsson]

Regarding this sometimes-add--latomic(-in-testsuite) that is
revisited:

When is it appropriate to make the user add -latomic to link
their program?  Perhaps different answers for fortran and C++.
I'm guessing "always when using any atomic construct" for C.

I had a grep-look in gcc/doc before asking; I can't see we say
anything.

I don't think "when the target lacks certain atomic features" is
a full valid answer, except pragmatically, to paper over a bug.

brgds, H-P
PS. I'll do the patch if you (someone) does the words.