Filesystem has a dependency on /bin/sh (rhbz#1306489)

Fix wrong usage of posix.exec() and replace it with rpm.execute():

https://bugzilla.redhat.com/show_bug.cgi?id=1306489#c20

filesystem.spec

@@ -1,7 +1,7 @@
 Summary: The basic directory layout for a Linux system
 Name: filesystem
 Version: 3.18
-Release: 1%{?dist}
+Release: 2%{?dist}
 License: Public Domain
 URL: https://pagure.io/filesystem
 Source1: https://pagure.io/filesystem/raw/master/f/lang-exceptions
@@ -170,20 +170,8 @@ return 0
 %posttrans -p <lua>
 --# we need to restorecon on some dirs created in %pretrans or by other packages
 if posix.access ("/usr/sbin/restorecon", "x") then
-  local pid = posix.fork()
+  rpm.execute("/usr/sbin/restorecon", "/var", "/var/run", "/var/lock", "/sys", "/boot", "/dev", "/media", "/afs")
-  if pid == 0 then
+  rpm.execute("/usr/sbin/restorecon", "-r", "/usr/lib/debug")
-    posix.exec("/usr/sbin/restorecon", "/var")
-    posix.exec("/usr/sbin/restorecon", "/var/run")
-    posix.exec("/usr/sbin/restorecon", "/var/lock")
-    posix.exec("/usr/sbin/restorecon", "-r", "/usr/lib/debug/")
-    posix.exec("/usr/sbin/restorecon", "/sys")
-    posix.exec("/usr/sbin/restorecon", "/boot")
-    posix.exec("/usr/sbin/restorecon", "/dev")
-    posix.exec("/usr/sbin/restorecon", "/media")
-    posix.exec("/usr/sbin/restorecon", "/afs")
-  elseif pid > 0 then
-    posix.wait(pid)
-  end
 end
 
 %files content
@@ -322,6 +310,9 @@ end
 /var/yp
 
 %changelog
+* Tue Aug 09 2022 Martin Osvald <mosvald@redhat.com> - 3.18-2
+- Filesystem has a dependency on /bin/sh (rhbz#1306489)
+
 * Tue Jul 26 2022 Martin Osvald <mosvald@redhat.com> - 3.18-1
 - Filesystem has a dependency on /bin/sh (#1306489)
 - Add /usr/share/X11/fonts/ to default filesystem (#2107447)