enhanced libproc cgroup/cmdline support, exploited by top

enhanced libproc cgroup/cmdline support, exploited by top

Library Changes
. added PROC_EDITCMDLCVT flag
. added an internal (static) fill_cmdline_cvt function:
  - reads and "escapes" /proc/#/cmdline
  - returns result as a single string in a single vector
  - callers are guaranteed a cmdline (no more NULL)
. added vectorize_this_str function, exploited by
  fill_cgroup_cvt, fill_cmdline_cvt
. generalized read_cmdline function as read_unvectored, now
  exploited by fill_cgroup_cvt, fill_cmdline_cvt, read_cmdline
  ( cgroup and cmdline no longer need be converted to string )
  ( vectors before being transformed to final representation )
. fixed bug regarding skipped group numbers (when enabled)
. escape_str made responsible for all single byte translation
  with distinction between control chars + other unprintable
. added escaped_copy function for already escaped strings
. reorganized parts of proc_t to restore formatting standards
  ( displacement changes shouldn't matter with new version # )
. former ZAP_SUSEONLY #define now OOMEM_ENABLE
. added to library.map: escaped_copy; read_cmdline

Top Program Changes
. exploited the new PROC_EDITCMDLCVT provision
. eliminated now obsolete #include "proc/escape.h"
. changed the P_WCH display format if no kernel symbol table
. fixed very old bug in lflgs for out-of-view sort fields
. former ZAP_SUSEONLY #define now OOMEM_ENABLE

Ps Program Changes
. exploited the new PROC_EDITCMDLCVT provision
. exploited the new escaped_copy function
. consolidated pr_args and pr_comm into pr_argcom

Signed-off-by: Jan Görig <jgorig@redhat.com>