Fix compiler warning.

p_f_string_expr produced warning: implicit conversion loses integer precision: 'long' to 'Py_UCS4' (aka 'unsigned int') [-Wshorten-64-to-32]

Cython/Compiler/Parsing.pxd

@@ -70,7 +70,7 @@ cdef bint check_for_non_ascii_characters(unicode string)
 cdef p_string_literal(PyrexScanner s, kind_override=*)
 @cython.locals(i=Py_ssize_t, size=Py_ssize_t)
 cdef list p_f_string(PyrexScanner s, unicode_value, pos)
-@cython.locals(i=Py_ssize_t, size=Py_ssize_t, c=Py_UCS4, quote_char=Py_UCS4)
+@cython.locals(i=Py_ssize_t, size=Py_ssize_t, c=Py_UCS4, quote_char=Py_UCS4, NO_CHAR=Py_UCS4)
 cdef tuple p_f_string_expr(PyrexScanner s, unicode_value, pos, Py_ssize_t starting_index)
 cdef p_list_maker(PyrexScanner s)
 cdef p_comp_iter(PyrexScanner s, body)