Add two new breakpoints to L4Sys experiment that allow detecting that
execution terminated with an error: vga_console_blink() is called by the
kernel if JDB was entered (meaning we are hanging, e.g., due to an
assertion); also longjmp() is only used by PF handling code after no
valid page fault handling could be performed
Change-Id: Ice61039c4bd07815a316bbc0bdb39f3483d9a1da