configure: replace -Wp,-D_FORTIFY_SOURCE=2 by -D_FORTIFY_SOURCE=2:
configure: replace -Wp,-D_FORTIFY_SOURCE=2 by -D_FORTIFY_SOURCE=2:

We use(d) -Wp,-D_FORTIFY_SOURCE=2 because rpmbuild also uses it
(cf., /usr/lib/rpm/redhat/macros).
However, clang (3.3/4.2.1) complains about "argument unused during compilation";
hence, we resort to plain "-D_FORTIFY_SOURCE=2", which appears to work fine
also with `make rpm`. Well, worst case is that we miss a check that during
"normal" build, that is then caught by -Wp,-D_FORTIFY_SOURCE=2 during `make rpm`.

zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb