METALS-London zinc slides to 4-mth low on slow pick-up in China steel demand

(Adds analyst comment, details; updates prices) By Melanie Burton MELBOURNE, April 12 (Reuters) - London zinc fell to a four-month low on Thursday, tracking the prices of other steel materials as construction demand in China got off to a slow start in the usually strong second quarter. Markets came under pressure on Thursday as the threat of imminent U.S. military action in Syria rattled investors and sent oil prices higher on concerns about potential disruptions to supply and dist