Javadoc fixes for Java 8. Replace "<tt>Foo</tt>" with "{@code Foo}".

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk@1603932 13f79535-47bb-0310-9956-ffa450edef68
Javadoc fixes for Java 8. Replace "<tt>Foo</tt>" with "{@code Foo}".

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk@1603933 13f79535-47bb-0310-9956-ffa450edef68