Boost\libs\pool\test failed due to link error on MSVC

**Issue description:**
Found Boost\libs\pool\test https://github.com/boostorg/boost/commit/38d8e0e70e1ea9232914d8a212aed488e32c4b48 link error in a future release of MSVC. Could you please take a look?

**Reproduce steps:**

1. git clone -c core.autocrlf=true --recursive ​https://github.com/boostorg/boost.git Boost\src
2. open a VS 2017 x64 command prompt and browse to Boost\src
3. .\bootstrap
4. .\b2 headers variant=release --build-dir=..\out\x64rel address-model=64
5. .\b2 variant=release --build-dir=..\out\x64rel address-model=64
6. .\b2 -j4 variant=release --build-dir=..\out\x64rel libs\pool\test

**ErrorMessage:**
Creating library .\pool_msvc_compiler_bug_test.lib and object .\pool_msvc_compiler_bug_test.exp
pool_msvc_compiler_bug_test.obj : error LNK2019: unresolved external symbol "public: __cdecl boost::archive::codecvt_null::codecvt_null(unsigned __int64)" (??0?$codecvt_null@_W@archive@boost@@QEAA@_K@Z) referenced in function "public: void __cdecl boost::archive::codecvt_null::`default constructor closure'(void)" (??_F?$codecvt_null@_W@archive@boost@@QEAAXXZ)
.\pool_msvc_compiler_bug_test.exe : fatal error LNK1120: 1 unresolved externals