spec: fix sanlock dependency

* libvirt.spec.in (with_sanlock): On RHEL, don't force sanlock
on architectures where it isn't available.

libvirt.spec.in

@@ -174,8 +174,14 @@
 %endif
 
 # Enable sanlock library for lock management with QEMU
-%if 0%{?fedora} >= 16 || 0%{?rhel} >= 6
-%define with_sanlock  0%{!?_without_sanlock:%{server_drivers}}
+# Sanlock is available only on i686 x86_64 for RHEL
+%if 0%{?fedora} >= 16
+%define with_sanlock 0%{!?_without_sanlock:%{server_drivers}}
+%endif
+%if 0%{?rhel} >= 6
+%ifnarch i386 i586 i686 x86_64
+%define with_sanlock 0%{!?_without_sanlock:%{server_drivers}}
+%endif
 %endif
 
 # Disable some drivers when building without libvirt daemon.