Function libnghttp2_sys::nghttp2_check_header_name

pub unsafe extern "C" fn nghttp2_check_header_name(
    name: *const u8, 
    len: usize
) -> c_int

@function

Returns nonzero if HTTP header field name |name| of length |len| is valid according to http://tools.ietf.org/html/rfc7230#section-3.2

Because this is a header field name in HTTP2, the upper cased alphabet is treated as error.