Stack overflow libgtop when pathname of mmap()-ed file is too long

Stack-based buffer overflow in the glibtop_get_proc_map_s function in libgtop before 2.14.6 (libgtop2) allows local users to cause a denial of service (crash) and possibly execute arbitrary code via a process with a long filename that is mapped in its address space, which triggers the overflow in gnome-system-monitor.