lib: only include fetch.h where required

This results in a lot of places where limits.h was missing, so
this diff is larger than necessary.

include/xbps_api_impl.h

@@ -42,7 +42,6 @@
 #endif
 
 #include "queue.h"
-#include "fetch.h"
 #include "compat.h"
 
 #define EXTRACT_FLAGS	ARCHIVE_EXTRACT_SECURE_NODOTDOT | \