build: Drop libnatpmp from build system

CMakeLists.txt

@@ -121,11 +121,6 @@ option(REDUCE_EXPORTS "Attempt to reduce exported symbols in the resulting execu
 option(WERROR "Treat compiler warnings as errors." OFF)
 option(WITH_CCACHE "Attempt to use ccache for compiling." ON)
 
-option(WITH_NATPMP "Enable NAT-PMP." OFF)
-if(WITH_NATPMP)
-  find_package(NATPMP MODULE REQUIRED)
-endif()
-
 option(WITH_MINIUPNPC "Enable UPnP." OFF)
 if(WITH_MINIUPNPC)
   find_package(MiniUPnPc MODULE REQUIRED)
@@ -239,7 +234,6 @@ if(BUILD_FOR_FUZZING)
   set(BUILD_WALLET_TOOL OFF)
   set(BUILD_GUI OFF)
   set(ENABLE_EXTERNAL_SIGNER OFF)
-  set(WITH_NATPMP OFF)
   set(WITH_MINIUPNPC OFF)
   set(WITH_ZMQ OFF)
   set(BUILD_TESTS OFF)
@@ -621,9 +615,7 @@ if(ENABLE_WALLET)
   message("   - legacy wallets (Berkeley DB) ..... ${WITH_BDB}")
 endif()
 message("  external signer ..................... ${ENABLE_EXTERNAL_SIGNER}")
-message("  port mapping:")
-message("   - using NAT-PMP .................... ${WITH_NATPMP}")
-message("   - using UPnP ....................... ${WITH_MINIUPNPC}")
+message("  port mapping using UPnP ............. ${WITH_MINIUPNPC}")
 message("  ZeroMQ .............................. ${WITH_ZMQ}")
 message("  USDT tracing ........................ ${WITH_USDT}")
 message("  QR code (GUI) ....................... ${WITH_QRENCODE}")