chunk: Don't depend on pthread directly

src/libstrongswan/utils/chunk.h

@@ -339,6 +339,14 @@ bool chunk_increment(chunk_t chunk);
  */
 bool chunk_printable(chunk_t chunk, chunk_t *sane, char replace);
 
+/**
+ * Seed initial key for chunk_hash().
+ *
+ * This call should get invoked once during startup. This is usually done
+ * by calling library_init().
+ */
+void chunk_hash_seed();
+
 /**
  * Computes a 32 bit hash of the given chunk.
  *