build: enforce makefile conditional style

Automake has builtin support to prevent botched conditional nesting,
but only if you use:
if FOO
else !FOO
endif !FOO

An example error message when using the wrong name:

daemon/Makefile.am:378: error: else reminder (LIBVIRT_INIT_SCRIPT_SYSTEMD_TRUE) incompatible with current conditional: LIBVIRT_INIT_SCRIPT_SYSTEMD_FALSE
daemon/Makefile.am:381: error: endif reminder (LIBVIRT_INIT_SCRIPT_SYSTEMD_TRUE) incompatible with current conditional: LIBVIRT_INIT_SCRIPT_SYSTEMD_FALSE

As our makefiles tend to have quite a bit of nested conditionals,
it's better to take advantage of the benefits of the build system
double-checking that our conditionals are well-nested, but that
requires a syntax check to enforce our usage style.

Alas, unlike C preprocessor and spec files, we can't use indentation
to make it easier to see how deeply nesting goes.

* cfg.mk (sc_makefile_conditionals): New rule.
* daemon/Makefile.am: Enforce the style.
* gnulib/tests/Makefile.am: Likewise.
* python/Makefile.am: Likewise.
* src/Makefile.am: Likewise.
* tests/Makefile.am: Likewise.
* tools/Makefile.am: Likewise.

Signed-off-by: Eric Blake <eblake@redhat.com>

daemon/Makefile.am

@@ -142,7 +142,7 @@ libvirtd_LDADD =					\
 
 if WITH_DTRACE_PROBES
 libvirtd_LDADD += ../src/libvirt_probes.lo
-endif
+endif WITH_DTRACE_PROBES
 
 libvirtd_LDADD += \
 	../src/libvirt-lxc.la \
@@ -153,53 +153,53 @@ if WITH_QEMU
     libvirtd_LDADD += ../src/libvirt_driver_qemu.la
 if WITH_DTRACE_PROBES
     libvirtd_LDADD += ../src/libvirt_qemu_probes.lo
-endif
-endif
+endif WITH_DTRACE_PROBES
+endif WITH_QEMU
 
 if WITH_LXC
     libvirtd_LDADD += ../src/libvirt_driver_lxc.la
-endif
+endif WITH_LXC
 
 if WITH_XEN
     libvirtd_LDADD += ../src/libvirt_driver_xen.la
-endif
+endif WITH_XEN
 
 if WITH_LIBXL
     libvirtd_LDADD += ../src/libvirt_driver_libxl.la
-endif
+endif WITH_LIBXL
 
 if WITH_UML
     libvirtd_LDADD += ../src/libvirt_driver_uml.la
-endif
+endif WITH_UML
 
 if WITH_VBOX
     libvirtd_LDADD += ../src/libvirt_driver_vbox.la
-endif
+endif WITH_VBOX
 
 if WITH_STORAGE
     libvirtd_LDADD += ../src/libvirt_driver_storage.la
-endif
+endif WITH_STORAGE
 
 if WITH_NETWORK
     libvirtd_LDADD += ../src/libvirt_driver_network.la
-endif
+endif WITH_NETWORK
 
 if WITH_INTERFACE
     libvirtd_LDADD += ../src/libvirt_driver_interface.la
-endif
+endif WITH_INTERFACE
 
 if WITH_NODE_DEVICES
     libvirtd_LDADD += ../src/libvirt_driver_nodedev.la
-endif
+endif WITH_NODE_DEVICES
 
 if WITH_SECRETS
     libvirtd_LDADD += ../src/libvirt_driver_secret.la
-endif
+endif WITH_SECRETS
 
 if WITH_NWFILTER
     libvirtd_LDADD += ../src/libvirt_driver_nwfilter.la
-endif
-endif
+endif WITH_NWFILTER
+endif ! WITH_DRIVER_MODULES
 
 libvirtd_LDADD += ../src/libvirt.la
 
@@ -207,11 +207,11 @@ if WITH_POLKIT
 if WITH_POLKIT0
 policydir = $(datadir)/PolicyKit/policy
 policyauth = auth_admin_keep_session
-else
+else ! WITH_POLKIT0
 policydir = $(datadir)/polkit-1/actions
 policyauth = auth_admin_keep
-endif
-endif
+endif ! WITH_POLKIT0
+endif WITH_POLKIT
 
 libvirtd.policy: libvirtd.policy.in $(top_builddir)/config.status
 	$(AM_V_GEN) sed \
@@ -243,10 +243,10 @@ install-data-polkit::
 uninstall-data-polkit::
 	rm -f $(DESTDIR)$(policydir)/org.libvirt.unix.policy
 	rmdir $(DESTDIR)$(policydir) || :
-else
+else ! WITH_POLKIT
 install-data-polkit::
 uninstall-data-polkit::
-endif
+endif ! WITH_POLKIT
 
 remote.c: $(DAEMON_GENERATED)
 remote.h: $(DAEMON_GENERATED)
@@ -323,10 +323,10 @@ install-sysctl:
 uninstall-sysctl:
 	rm -f $(DESTDIR)$(prefix)/lib/sysctl.d/libvirtd.conf
 	rmdir $(DESTDIR)$(prefix)/lib/sysctl.d || :
-else
+else ! WITH_SYSCTL
 install-sysctl:
 uninstall-sysctl:
-endif
+endif ! WITH_SYSCTL
 
 if LIBVIRT_INIT_SCRIPT_RED_HAT
 
@@ -340,10 +340,10 @@ install-init-redhat: install-sysconfig libvirtd.init
 uninstall-init-redhat: uninstall-sysconfig
 	rm -f $(DESTDIR)$(sysconfdir)/rc.d/init.d/libvirtd
 	rmdir $(DESTDIR)$(sysconfdir)/rc.d/init.d || :
-else
+else ! LIBVIRT_INIT_SCRIPT_RED_HAT
 install-init-redhat:
 uninstall-init-redhat:
-endif # LIBVIRT_INIT_SCRIPT_RED_HAT
+endif ! LIBVIRT_INIT_SCRIPT_RED_HAT
 
 
 if LIBVIRT_INIT_SCRIPT_UPSTART
@@ -356,10 +356,10 @@ install-init-upstart: install-sysconfig
 uninstall-init-upstart: uninstall-sysconfig
 	rm -f $(DESTDIR)$(sysconfdir)/event.d/libvirtd
 	rmdir $(DESTDIR)$(sysconfdir)/event.d || :
-else
+else ! LIBVIRT_INIT_SCRIPT_UPSTART
 install-init-upstart:
 uninstall-init-upstart:
-endif # LIBVIRT_INIT_SCRIPT_UPSTART
+endif ! LIBVIRT_INIT_SCRIPT_UPSTART
 
 
 if LIBVIRT_INIT_SCRIPT_SYSTEMD
@@ -375,10 +375,10 @@ install-init-systemd: install-sysconfig libvirtd.service
 uninstall-init-systemd: uninstall-sysconfig
 	rm -f $(DESTDIR)$(SYSTEMD_UNIT_DIR)/libvirtd.service
 	rmdir $(DESTDIR)$(SYSTEMD_UNIT_DIR) || :
-else
+else ! LIBVIRT_INIT_SCRIPT_SYSTEMD
 install-init-systemd:
 uninstall-init-systemd:
-endif # LIBVIRT_INIT_SCRIPT_SYSTEMD
+endif ! LIBVIRT_INIT_SCRIPT_SYSTEMD
 
 libvirtd.init: libvirtd.init.in $(top_builddir)/config.status
 	$(AM_V_GEN)sed						\
@@ -415,10 +415,10 @@ check-augeas: test_libvirtd.aug
 # are used by nearly every other library.
 libvirtd_LDADD += ../gnulib/lib/libgnu.la $(LIBSOCKET)
 
-else # WITH_LIBVIRTD
+else ! WITH_LIBVIRTD
 install-data-local: install-data-sasl
 uninstall-local:: uninstall-data-sasl
-endif # WITH_LIBVIRTD
+endif ! WITH_LIBVIRTD
 
 POD2MAN = pod2man -c "Virtualization Support" \
 			-r "$(PACKAGE)-$(VERSION)" -s 8
@@ -438,10 +438,10 @@ install-data-sasl:
 uninstall-data-sasl:
 	rm -f $(DESTDIR)$(sysconfdir)/sasl2/libvirt.conf
 	rmdir $(DESTDIR)$(sysconfdir)/sasl2/ || :
-else
+else ! WITH_SASL
 install-data-sasl:
 uninstall-data-sasl:
-endif
+endif ! WITH_SASL
 
 
 CLEANFILES += $(BUILT_SOURCES) $(man8_MANS)