Add dtrace static probes in libvirtd

Adds initial support for dtrace static probes in libvirtd
daemon, assuming use of systemtap dtrace compat shim on
Linux. The probes are inserted for network client connect,
disconnect, TLS handshake states and authentication protocol
states.

This can be tested by running the xample program and then
attempting to connect with any libvirt client (virsh,
virt-manager, etc).

 # stap examples/systemtap/client.stp
  Client fd=44 connected readonly=0
  Client fd=44 auth polkit deny pid:24997,uid:500
  Client fd=44 disconnected
  Client fd=46 connected readonly=1
  Client fd=46 auth sasl allow test
  Client fd=46 disconnected

The libvirtd.stp file should also really not be required,
since it is duplicated info that is already available in
the main probes.d definition file. A script to autogenerate
the .stp file is needed, either in libvirtd tree, or better
as part of systemtap itself.

* Makefile.am: Add examples/systemtap subdir
* autobuild.sh: Disable dtrace for mingw32
* configure.ac: Add check for dtrace
* daemon/.gitignore: Ignore generated dtrace probe file
* daemon/Makefile.am: Build dtrace probe header & object
  files
* daemon/libvirtd.stp: SystemTAP convenience probeset
* daemon/libvirtd.c: Add connect/disconnect & TLS probes
* daemon/remote.c: Add SASL and PolicyKit auth probes
* daemon/probes.d: Master probe definition
* daemon/libvirtd.h: Add convenience macro for probes
  so that compilation is a no-op when dtrace is not available
* examples/systemtap/Makefile.am, examples/systemtap/client.stp
  Example systemtap script using dtrace probe markers
* libvirt.spec.in: Enable dtrace on F13/RHEL6
* mingw32-libvirt.spec.in: Force disable dtrace

libvirt.spec.in

@@ -67,6 +67,7 @@
 %define with_macvtap       0%{!?_without_macvtap:0}
 %define with_libnl         0%{!?_without_libnl:0}
 %define with_audit         0%{!?_without_audit:0}
+%define with_dtrace        0%{!?_without_dtrace:0}
 
 # Non-server/HV driver defaults which are always enabled
 %define with_python        0%{!?_without_python:1}
@@ -170,6 +171,10 @@
 %define with_audit    0%{!?_without_audit:1}
 %endif
 
+%if 0%{?fedora} >= 13 || 0%{?rhel} >= 6
+%define with_dtrace 1
+%endif
+
 # Force QEMU to run as non-root
 %if 0%{?fedora} >= 12 || 0%{?rhel} >= 6
 %define qemu_user  qemu
@@ -564,6 +569,10 @@ of recent versions of Linux (and other OSes).
 %define _without_audit --without-audit
 %endif
 
+%if ! %{with_dtrace}
+%define _without_dtrace --without-dtrace
+%endif
+
 %configure %{?_without_xen} \
            %{?_without_qemu} \
            %{?_without_openvz} \
@@ -596,6 +605,7 @@ of recent versions of Linux (and other OSes).
            %{?_without_libpcap} \
            %{?_without_macvtap} \
            %{?_without_audit} \
+           %{?_without_dtrace} \
            --with-qemu-user=%{qemu_user} \
            --with-qemu-group=%{qemu_group} \
            --with-init-script=redhat \
@@ -607,7 +617,7 @@ gzip -9 ChangeLog
 rm -fr %{buildroot}
 
 %makeinstall
-for i in domain-events/events-c dominfo domsuspend hellolibvirt openauth python xml/nwfilter
+for i in domain-events/events-c dominfo domsuspend hellolibvirt openauth python xml/nwfilter systemtap
 do
   (cd examples/$i ; make clean ; rm -rf .deps .libs Makefile Makefile.in)
 done
@@ -763,6 +773,9 @@ fi
 %{_sysconfdir}/rc.d/init.d/libvirtd
 %config(noreplace) %{_sysconfdir}/sysconfig/libvirtd
 %config(noreplace) %{_sysconfdir}/libvirt/libvirtd.conf
+%if %{with_dtrace}
+%{_datadir}/systemtap/tapsets/libvirtd.stp
+%endif
 %dir %attr(0700, root, root) %{_localstatedir}/log/libvirt/qemu/
 %dir %attr(0700, root, root) %{_localstatedir}/log/libvirt/lxc/
 %dir %attr(0700, root, root) %{_localstatedir}/log/libvirt/uml/
@@ -909,6 +922,7 @@ fi
 %doc examples/domsuspend
 %doc examples/openauth
 %doc examples/xml
+%doc examples/systemtap
 
 %if %{with_python}
 %files python