Make gen-libm-test.py treat plus_oflow and minus_oflow as non-finite.

When converting gen-libm-test to Python, in one place I noted a bug in
the old Perl version that I preserved in the Python version so that
the generated output files were the same with both versions, as such
comparisons help give confidence in the correctness of such a rewrite
of a script.  Now that the conversion has been done, this patch fixes
that bug, by arranging for tests with plus_oflow or minus_oflow
results (manually written tests in libm-test-*.inc that have
overflowing results that thus depend on the rounding mode) to be
properly treated as having non-finite results, and thus not run for
the __FINITE_MATH_ONLY__ tests.  (As the affected tests in fact did
pass for __FINITE_MATH_ONLY__ testing, this is just a matter of
logical correctness in the choice of which tests run for that case,
rather than fixing any actual test failures.)

Tested for x86_64.

	* math/gen-libm-test.py (gen_test_args_res): Also treat plus_oflow
	and minus_oflow as non-finite.

math/gen-libm-test.py

@@ -308,9 +308,7 @@ def apply_lit(arg, macro):
 def gen_test_args_res(descr_args, descr_res, args, res_rm):
     """Generate a test given the arguments and per-rounding-mode results."""
     # Determine whether any arguments or results, for any rounding
-    # mode, are non-finite.  (For consistency with the old perl
-    # script, this does not handle infinities resulting from
-    # ROUNDING_MAP.)
+    # mode, are non-finite.
     non_finite = False
     test_snan = False
     all_args_res = list(args)
@@ -320,7 +318,8 @@ def gen_test_args_res(descr_args, descr_res, args, res_rm):
         if 'snan_value' in a:
             test_snan = True
             non_finite = True
-        elif 'qnan_value' in a or 'plus_infty' in a or 'minus_infty' in a:
+        elif ('qnan_value' in a or 'plus_infty' in a or 'minus_infty' in a
+              or 'plus_oflow' in a or 'minus_oflow' in a):
             non_finite = True
     # Process the arguments.
     args_disp = []