build-sys: Drop autoconf bits to find dbus service directory

We set it to the same value in both cases.  There's no reason
to require it at build time anyways.

Part of thinning out the Autotools side in prep for using Cargo.

Makefile-daemon.am

@@ -87,7 +87,7 @@ rpm-ostreed: $(srcdir)/src/daemon/rpm-ostreed-stub.sh.in Makefile
 # We don't yet rename the DBus related items
 service_in_files = $(srcdir)/src/daemon/org.projectatomic.rpmostree1.service.in
 service_DATA     = $(service_in_files:.service.in=.service)
-servicedir       = $(dbusservicedir)
+servicedir       = $(datadir)/dbus-1/system-services
 %.service: %.service.in Makefile
 	$(SED_SUBST) $@.in > $@.tmp && mv $@.tmp $@
 

configure.ac

@@ -27,19 +27,6 @@ dnl if not set, which we definitely want; cmake doesn't do that.
 AC_PROG_CXX
 AM_PROG_CC_C_O
 
-# dbus system dir
-AC_MSG_CHECKING(for dbus system services directory)
-if test "$enable_prefix_only" = "yes"; then
-  dbusservicedir='${datadir}/dbus-1/system-services'
-else
-  dbusservicedir='${datadir}/dbus-1/system-services'
-  if test "$dbusservicedir" = ""; then
-    AC_MSG_ERROR(Couldn't find dbus services directory. Try installing dbus-devel)
-  fi
-fi
-AC_SUBST([dbusservicedir], [$dbusservicedir])
-AC_MSG_RESULT(dbusservicedir)
-
 dnl Keep this in sync with the version in ostree
 AS_IF([echo "$CFLAGS" | grep -q -E -e '-Werror($| )'], [], [
 CC_CHECK_FLAGS_APPEND([WARN_CFLAGS], [CFLAGS], [\