BF: fix tests for binary128 / longdouble

Tests for windows float96 failing because of a change in the logic of
the type_info routine, so the routine was not returning after it
identifies windows float96.

Test for binary128 failing because Intel 80 float128 has the same
exponent precision and width, on 64 bit platforms.  Add nmant == 112
test.

Author: matthew-brett

nibabel/casting.py

@@ -252,6 +252,7 @@ def type_info(np_type):
         # at float64 precision. The finfo values give nexp == 15 (as for intel
         # 80) but in calculations nexp in fact appears to be 11 as for float64
         ret.update(dict(width=width))
+        return ret
     # Oh dear, we don't recognize the type information.  Try some known types
     # and then give up. At this stage we're expecting exotic longdouble or their
     # complex equivalent.

nibabel/tests/test_floating.py

@@ -263,7 +263,8 @@ def test_floor_exact():
 def test_usable_binary128():
     # Check for usable binary128
     yes = have_binary128()
-    abf = np.longdouble(2) ** 16383
+    exp_test = np.longdouble(2) ** 16383
     assert_equal(yes,
-                 abf.dtype.itemsize == 16 and
-                 np.isfinite(abf))
+                 exp_test.dtype.itemsize == 16 and
+                 np.isfinite(exp_test) and
+                 _check_nmant(np.longdouble, 112))