Use smaller ints as basis for some enum classes

And reorder class members in one case to make the memory footprint
smaller.

Author: joto

src/middle-pgsql.cpp

@@ -235,18 +235,18 @@ class member_list_json_builder
     }
 
 private:
-    osmium::builder::RelationMemberListBuilder *m_builder;
     std::string m_role;
+    osmium::builder::RelationMemberListBuilder *m_builder;
     osmium::object_id_type m_ref = 0;
     osmium::item_type m_type = osmium::item_type::undefined;
-    enum class next_val
+    enum class next_val : std::uint8_t
     {
         none,
         type,
         ref,
         role
     } m_next_val = next_val::none;
-};
+}; // class member_list_json_builder
 
 template <typename T>
 void pgsql_parse_json_members(char const *string,

src/output-flex.hpp

@@ -40,7 +40,7 @@ struct options_t;
  * When C++ code is called from the Lua code we sometimes need to know
  * in what context this happens. These are the possible contexts.
  */
-enum class calling_context
+enum class calling_context : std::uint8_t
 {
     main = 0, ///< In main context, i.e. the Lua script outside any callbacks
     process_node = 1, ///< In the process_node() callback

src/taginfo.hpp

@@ -10,10 +10,11 @@
  * For a full list of authors see the git log.
  */
 
+#include <cstdint>
 #include <string>
 #include <vector>
 
-enum class ColumnType
+enum class ColumnType : std::uint8_t
 {
     INT,
     REAL,

tests/test-output-flex-nodes.cpp

@@ -53,7 +53,7 @@ TEST_CASE("add nodes")
     CHECK(1 == conn.get_count("osm2pgsql_test_t1", "node_id = 17"));
 }
 
-enum class node_relationship
+enum class node_relationship : std::uint8_t
 {
     none,
     in_way,