VIENNA — Death and desperation mounted in Europe’s migrants crisis Friday as Austrian police said 71 people appeared to have suffocated in the back of an abandoned truck, while an estimated 200 people were feared drowned off Libya when two overloaded boats capsized. The death of 71 people locked in the truck on a highway south of Vienna shows “the desperation of people seeking protection or a new life in Europe,” said Melissa Fleming, spokeswoman for the U.N.