Turned out that there where a few () around macro args uses missing.
One real problem with it was detected with the int-in-bool-context in
the definition of DBX_REGISTER_NUMBER. But while being at it I've
also tried to fix other places where brackets might be missing.

gcc/ChangeLog:

2016-10-10  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* config/s390/s390.h: Wrap more macros args in brackets and fix
        some formatting.

From-SVN: r240930