build, wallet, doc: Remove BDB

CMakeLists.txt

@@ -110,22 +110,6 @@ if(ENABLE_WALLET)
     find_package(SQLite3 3.7.17 REQUIRED)
   endif()
 endif()
-option(WITH_BDB "Enable Berkeley DB (BDB) wallet support." OFF)
-cmake_dependent_option(WARN_INCOMPATIBLE_BDB "Warn when using a Berkeley DB (BDB) version other than 4.8." ON "WITH_BDB" OFF)
-if(WITH_BDB)
-  find_package(BerkeleyDB 4.8 MODULE REQUIRED)
-  set(USE_BDB ON)
-  if(NOT BerkeleyDB_VERSION VERSION_EQUAL 4.8)
-    message(WARNING "Found Berkeley DB (BDB) other than 4.8.\n"
-                    "BDB (legacy) wallets opened by this build will not be portable!"
-    )
-    if(WARN_INCOMPATIBLE_BDB)
-      message(WARNING "If this is intended, pass \"-DWARN_INCOMPATIBLE_BDB=OFF\".\n"
-                      "Passing \"-DWITH_BDB=OFF\" will suppress this warning."
-      )
-    endif()
-  endif()
-endif()
 cmake_dependent_option(BUILD_WALLET_TOOL "Build bitcoin-wallet tool." ${BUILD_TESTS} "ENABLE_WALLET" OFF)
 
 option(REDUCE_EXPORTS "Attempt to reduce exported symbols in the resulting executables." OFF)
@@ -677,9 +661,6 @@ message("  bitcoin-chainstate (experimental) ... ${BUILD_UTIL_CHAINSTATE}")
 message("  libbitcoinkernel (experimental) ..... ${BUILD_KERNEL_LIB}")
 message("Optional features:")
 message("  wallet support ...................... ${ENABLE_WALLET}")
-if(ENABLE_WALLET)
-  message("   - legacy wallets (Berkeley DB) ..... ${WITH_BDB}")
-endif()
 message("  external signer ..................... ${ENABLE_EXTERNAL_SIGNER}")
 message("  ZeroMQ .............................. ${WITH_ZMQ}")
 if(ENABLE_IPC)