`__bolt_instr_data_dump()` will find instrumented binary name by
iterating through entries under directory `/proc/self/map_files`,
and then open the binary and memory map it onto heap in order
to locate `.bolt.instr.tables` section to read the descriptions.
If binary name is already known and/or binary is already opened
as memory mapped, we can pass binary name and/or memory
buffer directly to `__bolt_instr_data_dump()` to save some work.
dadaa7941d