Subsections of type DEBUG_SYMBOL_SUBSECTION consist of a series of records. Each record begins with a 4 byte length, followed by 4 byte type, followed by <length> bytes of data.
This was already known, but we only dumped DEBUG_SYMBOL_TYPE_PROC_START and DEBUG_SYMBOL_TYPE_PROC_END. This patch makes llvm-readobj dump the Length, type, and payload of other types of entries as individaul records so that they can be studied more closely.