Drop requirement of confuse header for the public API; it's only used by libxbps.

include/xbps_api.h.in

@@ -33,7 +33,6 @@
 #include <archive.h>
 #include <archive_entry.h>
 #include <prop/proplib.h>
-#include <confuse.h>
 
 /**
  * @file include/xbps_api.h
@@ -430,6 +429,10 @@ struct xbps_unpack_cb_data {
 	bool entry_is_conf;
 };
 
+#ifndef LIBXBPS_PRIVATE
+typedef void *cfg_t;
+#endif
+
 /**
  * @struct xbps_handle xbps_api.h "xbps_api.h"
  * @brief Generic XBPS structure handler for initialization.

include/xbps_api_impl.h

@@ -32,6 +32,8 @@
 #endif
 
 #include <assert.h>
+#include <confuse.h>
+#define LIBXBPS_PRIVATE
 #include <xbps_api.h>
 /*
  * By default all public functions have default visibility, unless