Add missing standard includes to hll and cpc internal headers

coupon_iterator.hpp uses uint32_t and std::input_iterator_tag, and
compression_data.hpp uses uint8_t and uint16_t, but neither includes the
headers that declare them. Both compile today only because of include
order. This is the same latent problem as reverse_purge_hash_map.hpp in
#499, which surfaced under GCC 15's reduced transitive includes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: leerho

cpc/include/compression_data.hpp

@@ -22,6 +22,8 @@
 #ifndef CPC_COMPRESSION_DATA_HPP_
 #define CPC_COMPRESSION_DATA_HPP_
 
+#include <cstdint>
+
 namespace datasketches {
 
 /*

hll/include/coupon_iterator.hpp

@@ -20,6 +20,9 @@
 #ifndef _INTARRAYPAIRITERATOR_HPP_
 #define _INTARRAYPAIRITERATOR_HPP_
 
+#include <cstdint>
+#include <iterator>
+
 namespace datasketches {
 
 template<typename A>