build: silence libtool warning on probes.o

Libtool supports linking directly against .o files on some platforms
(such as Linux), which happens to be the only place where we are
actually doing that (for the dtrace-generated probes.o files).  However,
it raises a big stink about the non-portability, even though we don't
attempt it on platforms where it would actually fail:

  CCLD   libvirt_driver_qemu.la

*** Warning: Linking the shared library libvirt_driver_qemu.la against
the non-libtool
*** objects  libvirt_qemu_probes.o is not portable!

This shuts libtool up by creating a proper .lo file that matches
what libtool normally expects.

* src/Makefile.am (%_probes.lo): New rule.
(libvirt_probes.stp, libvirt_qemu_probes.stp): Simplify into...
(%_probes.stp): ...shorter rule.
(CLEANFILES): Clean new .lo files.
(libvirt_la_BUILT_LIBADD, libvirt_driver_qemu_la_LIBADD)
(libvirt_lxc_LDADD, virt_aa_helper_LDADD): Link against .lo file.
* tests/Makefile.am (PROBES_O, qemu_LDADDS): Likewise.

src/Makefile.am

@@ -1246,7 +1246,7 @@ libvirt_la_CFLAGS = -DIN_LIBVIRT $(AM_CFLAGS)
 libvirt_la_DEPENDENCIES = $(libvirt_la_BUILT_LIBADD) $(LIBVIRT_SYMBOL_FILE)
 
 if WITH_DTRACE_PROBES
-libvirt_la_BUILT_LIBADD += libvirt_probes.o
+libvirt_la_BUILT_LIBADD += libvirt_probes.lo
 libvirt_la_DEPENDENCIES += libvirt_probes.o
 nodist_libvirt_la_SOURCES = libvirt_probes.h
 if WITH_REMOTE
@@ -1256,7 +1256,7 @@ endif WITH_REMOTE
 BUILT_SOURCES += libvirt_probes.h libvirt_probes.stp libvirt_functions.stp
 
 if WITH_QEMU
-libvirt_driver_qemu_la_LIBADD += libvirt_qemu_probes.o
+libvirt_driver_qemu_la_LIBADD += libvirt_qemu_probes.lo
 nodist_libvirt_driver_qemu_la_SOURCES = libvirt_qemu_probes.h
 libvirt_driver_qemu_la_DEPENDENCIES = libvirt_qemu_probes.o
 
@@ -1272,6 +1272,15 @@ tapset_DATA = libvirt_probes.stp libvirt_qemu_probes.stp libvirt_functions.stp
 %_probes.o: %_probes.d
 	$(AM_V_GEN)$(DTRACE) -o $@ -G -s $<
 
+%_probes.lo: %_probes.o
+	$(AM_V_GEN)printf %s\\n \
+	  '# $@ - a libtool object file' \
+	  '# Generated by libtool (GNU libtool) 2.4' \
+	  '# Actually generated by Makefile.am, in order to shut up libtool' \
+	  "pic_object='$<'" \
+	  "non_pic_object='$<'" \
+	> $@
+
 RPC_PROBE_FILES = $(srcdir)/rpc/virnetprotocol.x \
 		  $(srcdir)/rpc/virkeepaliveprotocol.x \
 		  $(srcdir)/remote/remote_protocol.x \
@@ -1280,14 +1289,13 @@ RPC_PROBE_FILES = $(srcdir)/rpc/virnetprotocol.x \
 libvirt_functions.stp: $(RPC_PROBE_FILES) $(srcdir)/rpc/gensystemtap.pl
 	$(AM_V_GEN)perl -w $(srcdir)/rpc/gensystemtap.pl $(RPC_PROBE_FILES) > $@
 
-libvirt_probes.stp: libvirt_probes.d $(srcdir)/dtrace2systemtap.pl
-	$(AM_V_GEN)perl -w $(srcdir)/dtrace2systemtap.pl $(bindir) $(sbindir) $(libdir) $< > $@
-
-libvirt_qemu_probes.stp: libvirt_qemu_probes.d $(srcdir)/dtrace2systemtap.pl
-	$(AM_V_GEN)perl -w $(srcdir)/dtrace2systemtap.pl $(bindir) $(sbindir) $(libdir) $< > $@
+%_probes.stp: %_probes.d $(srcdir)/dtrace2systemtap.pl
+	$(AM_V_GEN)perl -w $(srcdir)/dtrace2systemtap.pl \
+	  $(bindir) $(sbindir) $(libdir) $< > $@
 
-CLEANFILES += libvirt_probes.h libvirt_probes.o \
+CLEANFILES += libvirt_probes.h libvirt_probes.o libvirt_probes.lo \
               libvirt_qemu_probes.h libvirt_qemu_probes.o \
+              libvirt_qemu_probes.lo\
               libvirt_functions.stp libvirt_probes.stp \
               libvirt_qemu_probes.stp
 endif
@@ -1479,7 +1487,7 @@ libvirt_lxc_LDADD = $(CAPNG_LIBS) $(YAJL_LIBS) \
 		$(RT_LIBS) $(DBUS_LIBS) \
 		../gnulib/lib/libgnu.la
 if WITH_DTRACE_PROBES
-libvirt_lxc_LDADD += libvirt_probes.o
+libvirt_lxc_LDADD += libvirt_probes.lo
 endif
 if WITH_SECDRIVER_SELINUX
 libvirt_lxc_LDADD += $(SELINUX_LIBS)
@@ -1524,7 +1532,7 @@ virt_aa_helper_LDADD =						\
 		libvirt_util.la					\
 		../gnulib/lib/libgnu.la
 if WITH_DTRACE_PROBES
-virt_aa_helper_LDADD += libvirt_probes.o
+virt_aa_helper_LDADD += libvirt_probes.lo
 endif
 virt_aa_helper_CFLAGS =						\
 		-I$(top_srcdir)/src/conf			\

tests/Makefile.am

@@ -31,7 +31,7 @@ endif
 
 PROBES_O =
 if WITH_DTRACE_PROBES
-PROBES_O += ../src/libvirt_probes.o
+PROBES_O += ../src/libvirt_probes.lo
 endif
 
 LDADDS = \
@@ -295,7 +295,7 @@ if WITH_NETWORK
 qemu_LDADDS += ../src/libvirt_driver_network.la
 endif
 if WITH_DTRACE_PROBES
-qemu_LDADDS += ../src/libvirt_qemu_probes.o
+qemu_LDADDS += ../src/libvirt_qemu_probes.lo
 endif
 qemu_LDADDS += $(LDADDS)