To safeguard against non-refcounted objects being left over in a log info piece (e.g. a string on the stack), add this new function to pop pieces from the stack until the desired one is removed. This is needed in case of a unpaired log_info_* without a matching log_info_pop. closes #1511 Change-Id: I689de14d034df779521dfdf59f923fdbf7fabc9bpull/1525/head