[analyzer] Add the type of the leaked object to the diagnostic message

[analyzer] Add the type of the leaked object to the diagnostic message

If the object is a temporary, and there is no variable it binds to,
let's at least print out the object name in order to help differentiate
it from other temporaries.

rdar://45175098

Differential Revision: https://reviews.llvm.org/D55033

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@347943 91177308-0d34-0410-b5e6-96231b3b80d8