drop some useless micro 'optimisations' in Py3

--HG--
extra : transplant_source : fE%C2RT%7EHt%958%F4%257o%00%CB%3B%C3%B7%BA

Cython/Utility/FunctionArguments.c

@@ -125,7 +125,7 @@ static CYTHON_INLINE int __Pyx_CheckKeywordStrings(
         #if PY_MAJOR_VERSION < 3
         if (unlikely(!PyString_CheckExact(key)) && unlikely(!PyString_Check(key)))
         #else
-        if (unlikely(!PyUnicode_CheckExact(key)) && unlikely(!PyUnicode_Check(key)))
+        if (unlikely(!PyUnicode_Check(key)))
         #endif
             goto invalid_keyword_type;
     }
@@ -193,7 +193,7 @@ static int __Pyx_ParseOptionalKeywords(
             #if PY_MAJOR_VERSION < 3
             if (unlikely(!PyString_CheckExact(key)) && unlikely(!PyString_Check(key))) {
             #else
-            if (unlikely(!PyUnicode_CheckExact(key)) && unlikely(!PyUnicode_Check(key))) {
+            if (unlikely(!PyUnicode_Check(key))) {
             #endif
                 goto invalid_keyword_type;
             } else {