build: clarify systemd-login build flags

systemd gets used for more than just systemd-login.

configure.ac

@@ -290,14 +290,14 @@ fi
 case $with_session_tracking in
     ck|none|no) ;;
     systemd)
-        PKG_CHECK_MODULES(SYSTEMD, [libsystemd-login])
+        PKG_CHECK_MODULES(SYSTEMD_LOGIN, [libsystemd-login])
         ;;
     *)
 	AC_MSG_ERROR(--with-session-tracking must be one of [none, ck, systemd])
         ;;
 esac
-AC_SUBST(SYSTEMD_CFLAGS)
-AC_SUBST(SYSTEMD_LIBS)
+AC_SUBST(SYSTEMD_LOGIN_CFLAGS)
+AC_SUBST(SYSTEMD_LOGIN_LIBS)
 AC_SUBST(CKDB_PATH, /var/run/ConsoleKit/database)
 AM_CONDITIONAL(SESSION_TRACKING_CK, test "x$with_session_tracking" = "xck")
 AM_CONDITIONAL(SESSION_TRACKING_SYSTEMD, test "x$with_session_tracking" = "xsystemd")

src/Makefile.am

@@ -292,7 +292,7 @@ NetworkManager_CPPFLAGS = \
 	$(GUDEV_CFLAGS) \
 	$(LIBNL_CFLAGS) \
 	$(POLKIT_CFLAGS) \
-	$(SYSTEMD_CFLAGS) \
+	$(SYSTEMD_LOGIN_CFLAGS) \
 	-DBINDIR=\"$(bindir)\" \
 	-DSBINDIR=\"$(sbindir)\" \
 	-DLIBEXECDIR=\"$(libexecdir)\" \
@@ -336,7 +336,7 @@ NetworkManager_LDADD = \
 	$(GUDEV_LIBS) \
 	$(LIBNL_LIBS) \
 	$(POLKIT_LIBS) \
-	$(SYSTEMD_LIBS) \
+	$(SYSTEMD_LOGIN_LIBS) \
 	$(LIBM) \
 	$(LIBDL)
 

src/generated/Makefile.am

@@ -67,7 +67,7 @@ libnm_generated_la_CPPFLAGS = \
 	$(GUDEV_CFLAGS) \
 	$(LIBNL_CFLAGS) \
 	$(POLKIT_CFLAGS) \
-	$(SYSTEMD_CFLAGS) \
+	$(SYSTEMD_LOGIN_CFLAGS) \
 	$(IWMX_SDK_CFLAGS)
 
 libnm_generated_la_LIBADD = \