MINOR: tools: let dump_addr_and_bytes() support dumping before the offset
For code dumps, dumping from the return address is pointless, what is
interesting is to dump before the return address to read the machine
code that was executed before branching. Let's just make the function
support negative sizes to indicate that we're dumping this number of
bytes to the address instead of this number from the address. In this
case, in order to distinguish them, we're using a '<' instead of '[' to
start the series of bytes, indicating where the bytes expand and where
they stop. For example we can now see this: