build: rename build-related dirs

Problem:
Dirs "config", "packaging", and "third-party" are all closely related
but this is not obvious from the layout. This adds friction for new
contributors.

Solution:
- rename config/ to cmake.config/
- rename test/config/ to test/cmakeconfig/ because it is used in Lua
  tests: require('test.cmakeconfig.paths').
- rename packaging/ to cmake.packaging/
- rename third-party/ to cmake.deps/ (parallel with .deps/)

cmake.deps/cmake/BuildLua.cmake

@@ -0,0 +1,96 @@
+# BuildLua(CONFIGURE_COMMAND ... BUILD_COMMAND ... INSTALL_COMMAND ...)
+# Reusable function to build lua, wraps ExternalProject_Add.
+# Failing to pass a command argument will result in no command being run
+function(BuildLua)
+  cmake_parse_arguments(_lua
+    ""
+    ""
+    "CONFIGURE_COMMAND;BUILD_COMMAND;INSTALL_COMMAND"
+    ${ARGN})
+
+  if(NOT _lua_CONFIGURE_COMMAND AND NOT _lua_BUILD_COMMAND
+       AND NOT _lua_INSTALL_COMMAND)
+    message(FATAL_ERROR "Must pass at least one of CONFIGURE_COMMAND, BUILD_COMMAND, INSTALL_COMMAND")
+  endif()
+
+  ExternalProject_Add(lua
+    PREFIX ${DEPS_BUILD_DIR}
+    URL ${LUA_URL}
+    DOWNLOAD_DIR ${DEPS_DOWNLOAD_DIR}/lua
+    DOWNLOAD_COMMAND ${CMAKE_COMMAND}
+      -DPREFIX=${DEPS_BUILD_DIR}
+      -DDOWNLOAD_DIR=${DEPS_DOWNLOAD_DIR}/lua
+      -DURL=${LUA_URL}
+      -DEXPECTED_SHA256=${LUA_SHA256}
+      -DTARGET=lua
+      -DUSE_EXISTING_SRC_DIR=${USE_EXISTING_SRC_DIR}
+      -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/DownloadAndExtractFile.cmake
+    CONFIGURE_COMMAND "${_lua_CONFIGURE_COMMAND}"
+    BUILD_IN_SOURCE 1
+    BUILD_COMMAND "${_lua_BUILD_COMMAND}"
+    INSTALL_COMMAND "${_lua_INSTALL_COMMAND}")
+endfunction()
+
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+  set(LUA_TARGET linux)
+elseif(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+  set(LUA_TARGET macosx)
+elseif(CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
+  set(LUA_TARGET freebsd)
+elseif(CMAKE_SYSTEM_NAME MATCHES "BSD")
+  set(CMAKE_LUA_TARGET bsd)
+elseif(CMAKE_SYSTEM_NAME MATCHES "^MINGW")
+  set(CMAKE_LUA_TARGET mingw)
+else()
+  if(UNIX)
+    set(LUA_TARGET posix)
+  else()
+    set(LUA_TARGET generic)
+  endif()
+endif()
+
+set(LUA_CFLAGS "-O0 -g3 -fPIC")
+set(LUA_LDFLAGS "")
+
+if(CLANG_ASAN_UBSAN)
+  set(LUA_CFLAGS "${LUA_CFLAGS} -fsanitize=address")
+  set(LUA_CFLAGS "${LUA_CFLAGS} -fno-omit-frame-pointer")
+  set(LUA_CFLAGS "${LUA_CFLAGS} -fno-optimize-sibling-calls")
+
+  set(LUA_LDFLAGS "${LUA_LDFLAGS} -fsanitize=address")
+endif()
+
+set(LUA_CONFIGURE_COMMAND
+  sed -e "/^CC/s@gcc@${CMAKE_C_COMPILER} ${CMAKE_C_COMPILER_ARG1}@"
+      -e "/^CFLAGS/s@-O2@${LUA_CFLAGS}@"
+      -e "/^MYLDFLAGS/s@$@${LUA_LDFLAGS}@"
+      -e "s@-lreadline@@g"
+      -e "s@-lhistory@@g"
+      -e "s@-lncurses@@g"
+      -i ${DEPS_BUILD_DIR}/src/lua/src/Makefile &&
+  sed -e "/#define LUA_USE_READLINE/d"
+      -e "s@\\(#define LUA_ROOT[ 	]*\"\\)/usr/local@\\1${DEPS_INSTALL_DIR}@"
+      -i ${DEPS_BUILD_DIR}/src/lua/src/luaconf.h)
+set(LUA_INSTALL_TOP_ARG "INSTALL_TOP=${DEPS_INSTALL_DIR}")
+set(LUA_BUILD_COMMAND
+    ${MAKE_PRG} ${LUA_INSTALL_TOP_ARG} ${LUA_TARGET})
+set(LUA_INSTALL_COMMAND
+    ${MAKE_PRG} ${LUA_INSTALL_TOP_ARG} install)
+
+message(STATUS "Lua target is ${LUA_TARGET}")
+
+BuildLua(CONFIGURE_COMMAND ${LUA_CONFIGURE_COMMAND}
+  BUILD_COMMAND ${LUA_BUILD_COMMAND}
+  INSTALL_COMMAND ${LUA_INSTALL_COMMAND})
+list(APPEND THIRD_PARTY_DEPS lua)
+
+set(BUSTED ${DEPS_INSTALL_DIR}/bin/busted)
+set(BUSTED_LUA ${BUSTED}-lua)
+
+add_custom_command(OUTPUT ${BUSTED_LUA}
+  COMMAND sed -e 's/^exec/exec $$LUA_DEBUGGER/' -e 's/jit//g' < ${BUSTED} > ${BUSTED_LUA} && chmod +x ${BUSTED_LUA}
+  DEPENDS lua busted ${BUSTED})
+add_custom_target(busted-lua
+  DEPENDS ${DEPS_INSTALL_DIR}/bin/busted-lua)
+
+list(APPEND THIRD_PARTY_DEPS busted-lua)