ShowMessageBoxOnError allows us to enter 'yes' to attach to the failing process.

This is currently broken and gdb outputs:
/pr: No such file or directory.

The bug seems to be in os::start_debugging and the line:
jio_snprintf(buf, sizeof(buf), "gdb /proc/%d/exe %d",

buf is a char* and sizeof(buf) always returns 8 (or 4).

This is broken on multiple platforms.