Libcloudproviders has a single header entry point, so we shouldn't
include a sub-header.
Additionally, the include path provided by the pkg-config file is:
-I${includedir}/cloudproviders
So the include directive should be:
#include <cloudproviders.h>
The fact that it worked until now was an accident caused by the blanket:
-I${includedir}
we get for free; it broke the build when using libcloudproviders as a
subproject.
#include "gtkspinner.h"
#ifdef HAVE_CLOUDPROVIDERS
-#include <cloudproviders/cloudprovidersaccount.h>
+#include <cloudproviders.h>
#endif
struct _GtkSidebarRow