fix dfu plugin loading

failed to open plugin
/usr/lib/x86_64-linux-gnu/fwupd-plugins-2/libfu_plugin_dfu.so:
failed to open plugin:
/usr/lib/x86_64-linux-gnu/fwupd-plugins-2/libfu_plugin_dfu.so:
undefined symbol: dfu_device_upload

plugins/dfu/Makefile.am

@@ -6,12 +6,18 @@ AM_CPPFLAGS =						\
 	-I$(top_srcdir)/libfwupd			\
 	-I$(top_srcdir)/src
 
+DFU_LIBS =						\
+	$(top_builddir)/libdfu/libdfu.la
+
 plugindir = $(libdir)/fwupd-plugins-2
 plugin_LTLIBRARIES = libfu_plugin_dfu.la
 
 libfu_plugin_dfu_la_SOURCES =				\
 	fu-plugin-dfu.c
-libfu_plugin_dfu_la_LIBADD = $(GUSB_LIBS)
+libfu_plugin_dfu_la_LIBADD = 				\
+	$(GUSB_LIBS)					\
+	$(DFU_LIBS)
+
 libfu_plugin_dfu_la_LDFLAGS = -module -avoid-version
 libfu_plugin_dfu_la_CFLAGS = $(WARN_CFLAGS)		\
 	-DG_LOG_DOMAIN=\"FuPluginDfu\"

src/Makefile.am

@@ -30,9 +30,6 @@ AM_CPPFLAGS =						\
 FWUPD_LIBS =						\
 	$(top_builddir)/libfwupd/libfwupd.la
 
-DFU_LIBS =						\
-	$(top_builddir)/libdfu/libdfu.la
-
 bin_PROGRAMS = fwupdmgr
 
 fwupdmgr_SOURCES =					\
@@ -130,7 +127,6 @@ fwupd_SOURCES =						\
 
 fwupd_LDADD =						\
 	$(FWUPD_LIBS)					\
-	$(DFU_LIBS)					\
 	$(APPSTREAM_GLIB_LIBS)				\
 	$(GUSB_LIBS)					\
 	$(GCAB_LIBS)					\