trivial: Include the fwupd version in the useragent

See https://blogs.gnome.org/hughsie/2018/02/16/ for more details.

src/Makefile.am

@@ -9,6 +9,7 @@ AM_CPPFLAGS =						\
 	$(PACKAGEKIT_CFLAGS)				\
 	$(GNOME_DESKTOP_CFLAGS)				\
 	$(POLKIT_CFLAGS)				\
+	$(FWUPD_CFLAGS)					\
 	$(LIBSECRET_CFLAGS)				\
 	-DG_LOG_DOMAIN=\"Gs\"				\
 	-DI_KNOW_THE_PACKAGEKIT_GLIB2_API_IS_SUBJECT_TO_CHANGE	\

src/gs-utils.c

@@ -29,6 +29,10 @@
 #include <polkit/polkit.h>
 #endif
 
+#ifdef HAVE_FIRMWARE
+#include <fwupd.h>
+#endif
+
 #include "gs-app.h"
 #include "gs-utils.h"
 #include "gs-plugin.h"
@@ -409,7 +413,20 @@ gs_utils_get_file_age (GFile *file)
 const gchar *
 gs_user_agent (void)
 {
+#ifdef HAVE_FIRMWARE
+	static gchar *user_agent = NULL;
+	if (user_agent == NULL) {
+		user_agent = g_strdup_printf ("%s/%s fwupd/%i.%i.%i",
+					      PACKAGE_NAME,
+					      PACKAGE_VERSION,
+					      FWUPD_MAJOR_VERSION,
+					      FWUPD_MINOR_VERSION,
+					      FWUPD_MICRO_VERSION);
+	}
+	return user_agent;
+#else
 	return PACKAGE_NAME "/" PACKAGE_VERSION;
+#endif
 }
 
 /**