[Bug testsuite/83791] Move tests to libgomp.c-c++-common

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83791

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
Approved here: https://gcc.gnu.org/ml/gcc-patches/2018-02/msg00920.html .

Will commit in stage1.