RFR: 8257707: Fix incorrect format string in Http1HeaderParser

[Aleksey Shipilev]

On Sat, 28 Nov 2020 19:42:01 GMT, Andrey Turbanov <github.com+741251+turbanoff at openjdk.org> wrote:

> Incorrect format string was found by IntelliJ IDEA inspection `Java | Probable bugs | Malformed format string`

Looks good to me.

-------------

Marked as reviewed by shade (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1495