which static library define epan_init, etc?

Whether a library is static or dynamic depends on how it's built, not what it defines.

The libraries that define those functions are:

• epan_init - libwireshark
• proto_item_fill_label - libwireshark
• g_sprintf - glib
• g_assertion_message_expr - glib
• register_all_protocol_handoffs - libwireshark
• register_all_protocols - libwireshark
• frame_data_set_before_dissect - libwireshark
• g_malloc0 - glib

Whether the machine you're using has static versions of either of those libraries depends on how the libraries were built and, if GLib and Wireshark are provided as packages for your system, whether static versions of the libraries are provided in any of those packages and, if so, whether they're provided in a separate package and whether that package is installed on your machine.