locale.c: Move unreachable code

It turns out this code, setting errno, is unreachable.  Move it to the
place where it would do some good, removing an extraneous, unreachable
return;

locale.c

@@ -342,6 +342,12 @@ S_get_category_index(const int category, const char * locale)
                           "Unknown locale category %d%s%s",
                           category, conditional_warn_text, locale);
 
+#  ifdef EINVAL
+
+    SETERRNO(EINVAL, LIB_INVARG);
+
+#  endif
+
     /* Return an out-of-bounds value */
     return NOMINAL_LC_ALL_INDEX + 1;
 }
@@ -660,14 +666,6 @@ S_emulate_setlocale_i(pTHX_ const unsigned int index, const char * locale)
             return all_string;
         }
 
-#    ifdef EINVAL
-
-        SETERRNO(EINVAL, LIB_INVARG);
-
-#    endif
-
-        return NULL;
-
 #  endif
 
     }   /* End of this being setlocale(LC_foo, NULL) */