test: Finit against a real dbus-daemon

The other dbus-*.sh tests drive libink's own client, so the wire format
was only ever checked against the implementation that wrote it, and the
broker path had no coverage at all.  Every bug found in it so far was
found by hand on a target.

Let the dbus plugin bring up a real dbus-daemon, wait for Finit to
claim org.finit, then talk to Finit with dbus-send, which shares no
code with us.  The privileged call is the interesting one: it can only
be answered by parking the call and asking the broker who sent it.
The bus reads the policy Finit installs, so a malformed org.finit.conf
fails here rather than on a target.

Tests no longer build --with-libsystemd.  Our replacement carries the
real soname but only the sd_notify() symbols, so in the test root it
shadowed the libsystemd the host's libdbus-1 wants and dbus-daemon
died on a missing sd_is_socket.  Nothing under test needs the shared
library: serv is the only consumer and it compiles sd-daemon.c
straight in, which it now does regardless of the flag so notify.sh
keeps testing notify:systemd either way.

Staged from the host by lib/sysroot.mk like any other binary, and
skipped when the host has neither program.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

test/lib/sysroot.mk

@@ -36,11 +36,23 @@ BBURL          ?= $(BBHOME)/$(BBVER)/$(BBBIN)
 
 # glibc dlopen()s NSS modules at runtime, so ldd does not list them, but
 # without libnss_files getpwnam() cannot resolve users inside the chroot
-_libs_nss       = $(firstword $(wildcard /lib/$(ARCH)-linux-gnu/libnss_files.so.2 \
+_libs_nss      := $(firstword $(wildcard /lib/$(ARCH)-linux-gnu/libnss_files.so.2 \
                                          /usr/lib/$(ARCH)-linux-gnu/libnss_files.so.2 \
                                          /lib64/libnss_files.so.2 /lib/libnss_files.so.2))
-_libs_src       = $(shell ldd $(FINITBIN) | grep -Eo '/[^ ]+') $(_libs_nss)
-libs            = $(foreach path,$(_libs_src),$(abspath $(DEST))$(path))
+# A real broker and a real client, staged when the host has them, so
+# one test can check Finit against dbus-daemon instead of only against
+# libink's own client.  Absent is fine, dbus-broker.sh skips.
+dbus_bins      := $(foreach b,dbus-daemon dbus-send,$(firstword $(wildcard /usr/bin/$(b) /bin/$(b))))
+# Given several binaries ldd prefixes each with a 'path:' header, and
+# that trailing colon would land in a make target.  Excluding it here
+# is enough, no need for one ldd per binary.
+_libs_dbus     := $(if $(dbus_bins),$(shell ldd $(dbus_bins) | grep -Eo '/[^ :]+'))
+
+# The binaries stage exactly like the libraries: same host path, same
+# path under DEST, copied by the rule below.
+_libs_src      := $(shell ldd $(FINITBIN) | grep -Eo '/[^ ]+') $(_libs_nss) \
+                  $(_libs_dbus) $(dbus_bins)
+libs           := $(foreach path,$(sort $(_libs_src)),$(abspath $(DEST))$(path))
 
 all: $(libs) $(DEST)/bin/$(BBBIN)
 	@(cd $(DEST);					\