[15u notice] last 15u-dev merge for 15.0.4

[Yuri Nesterenko]

Hi,

jdk15u-dev is now closed. It will reopen for 15.0.5 release
soon, with jdk-15.0.5+0 tag set there.
Last update of master jdk15u repo from jdk15u-dev will be finished 
shortly. Further changes to 15.0.4, if any, would go directly to
jdk15u and should be requested with jdk15u-critical-request.

Thank you!
--yan