Use python libselinux bindings to determine policy version.

This eliminates the hardcoded /selinux in Rules.monolithic, which
broke when the filesystem mount was moved to /sys/fs/selinux.

Makefile

@@ -97,6 +97,7 @@ support := support
 genxml := $(PYTHON) -E $(support)/segenxml.py
 gendoc := $(PYTHON) -E $(support)/sedoctool.py
 genperm := $(PYTHON) -E $(support)/genclassperms.py
+policyvers := $(PYTHON) -E $(support)/policyvers.py
 fcsort := $(tmpdir)/fc_sort
 setbools := $(AWK) -f $(support)/set_bools_tuns.awk
 get_type_attr_decl := $(SED) -r -f $(support)/get_type_attr_decl.sed

Rules.monolithic

@@ -5,7 +5,7 @@
 
 # determine the policy version and current kernel version if possible
 pv := $(shell $(CHECKPOLICY) -V |cut -f 1 -d ' ')
-kv := $(shell cat /selinux/policyvers)
+kv := $(shell $(policyvers))
 
 # dont print version warnings if we are unable to determine
 # the currently running kernel's policy version

support/policyvers.py

@@ -0,0 +1,3 @@
+#!/usr/bin/python
+import selinux
+print selinux.security_policyvers()