* Asian stock markets: https://tmsnrt.rs/2zpUAr4* Asia ex-Japan hits 4-month low, China shares drop* Yen, sovereign bonds buoyed by safe-haven bid* Pound under pressure on reports PM May to quit* Oil prices nurse losses as inventories buildBy Wayne ColeSYDNEY, May 23 (Reuters) - Asian shares broke support and caved to a four-month low on Thursday, as concerns grew that the Sino-U.S. trade conflict