configure: fix check for sys/sysmacros.h under glibc 2.25+

configure: fix check for sys/sysmacros.h under glibc 2.25+

glibc 2.25 still includes sys/sysmacros.h in sys/types.h but also emits
deprecation warning. So test for sys/types.h succeeds in configure but later
compilation fails because we use -Werror by default.

While this is fixed in current autoconf GIT, we really cannot force everyone
to use bleeding edge (that is not even released right now). So run test under
-Werror as well to force proper detection.

This should have no impact on autoconf 2.70+ as AC_HEADER_MAJOR in this version
simply checks for header existence.

Reported and tested by Khem Raj <raj.khem@gmail.com>