我正在尝试使用 bjam.exe 编译 boost 1.49。我找到了命令行：
bjam.exe toolset=gcc variant=release threading=multi link=static boost_thread
但它会引发一些错误：
warning: mismatched versions of Boost.Build engine and core
warning: Boost.Build engine (bjam.exe) is 03.1.18
warning: Boost.Build core (at ./tools/build/vs) is 2011.04-svn
./tools/build/vs/tools/gcc.jam:129: in gcc.init from module gcc
error: toolset gcc initialization
error: no command provided, default command 'g++' not found
error: initialized from ./tools/build/v2/user-config.jam:42
./tools/build/v2/build/toolset.jam:38 in toolset.using from module toolset
./tools/build/v2/build/project.jam:888 in using from module project-rules
./tools/build/v2/user-config.jam:42 in modules.load from module user-config
./tools/build/v2/build-system.jam:257 in load-config from module build-system
./tools/build/v2/build-system.jam:399 in load-configuration-files from module build-system
./tools/build/v2/build-system.jam:555: in load from module build-system
./tools/build/v2/kernel/modules.jam:283: in import from module modules
./tools/build/v2/kernel/bootstrap.jam:142: in boost-build from module
./boost-build.jam:17: in module scope from module
我怎样才能让 bjam 知道 gcc 在哪里（我用 MinGW 和 Codeblocks 安装了它）？我怎样才能拥有正确的版本？