r265273 added Mapper::mapBlockAddress, which delays mapping a
blockaddress value until the function has a body. The condition was
backwards, and should be checking Function::empty instead of
GlobalValue::isDeclaration.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265508 91177308-0d34-0410-b5e6-96231b3b80d8