EL PASO — For years, Raul Martinez has enjoyed the view of his native Ciudad Juárez from his modest apartment complex on the south side of this border city.In a few months he could be forced to peer through an 18-foot-tall fence to get the same vantage point.That’s the reality for residents of the Chihuahita neighborhood, one of the oldest in the country, since U.S. Customs and Border Protection officials announced they'd be constructing a four-mile barrier just north of the Rio Grande River — mandated . . .