system.conf: base ipc permissions on process names rather than labels

From now on, the "ipc" directive in system.conf refers to process names
instead of labels, similar to the "control" directive. The old, more
fine-grained approach is deemed unnecessary and cumbersome at this time.

As side effects, this patch unbreaks late IPC permission computation as
well as the filter driver.

man/man5/system.conf.5

@@ -50,15 +50,15 @@ Many system services run with root privileges (uid \fB0\fR).
 The default user is service (uid \fB12\fR).
 .RE
 .PP
-\fBipc\fR \fI<ALL|ALL_SYS|NONE|label1 label2...labelN>\fR\fB;\fR
+\fBipc\fR \fI<ALL|ALL_SYS|NONE|name1 name2...nameN>\fR\fB;\fR
 .PP
 .RS
 specifies the list of ipc targets (processes and kernel) the system service can
 talk to. \fIALL\fR allows all the possible targets, \fIALL_SYS\fR is similar but
 excludes user processes. When an explicit list is given, each target
-must be identified by its label (assigned to the corresponding system service).
-Exceptions are user processes (use pseudo-label \fIUSER\fR) and
-the kernel for kernel calls (use pseudo-label \fISYSTEM\fR). The default is
+must be identified by its process (binary) name.
+Exceptions are user processes (use pseudo-name \fIUSER\fR) and
+the kernel for kernel calls (use pseudo-name \fISYSTEM\fR). The default is
 \fIALL_SYS\fR.
 .RE
 .PP
@@ -158,11 +158,11 @@ specifies the PCI classes the system service is allowed to use
 The default is to allow no PCI classes.
 .RE
 .PP
-\fBcontrol\fR \fI<label1 label2...labelN>\fR\fB;\fR
+\fBcontrol\fR \fI<name1 name2...nameN>\fR\fB;\fR
 .PP
 .RS
-specifies the list of system services (identified by their labels) that are
-allowed to control the system service. A controller service can ask RS
+specifies the list of system services (identified by their process names) that
+are allowed to control the system service. A controller service can ask RS
 to perform privileged actions like immediately restarting the service.
 The default is to allow no controller services.
 .RE