boostorg/exception failed due to error LNK2019 on MSVC

[QuellaZhang]

Environment: VS 2017 + Windows Server 2016

Issue description: Boostorg/exception failed to compile when updating Boost version to 68cc708 on MSVC. Could you please take a look?

log_x64_test_32.log

Reproduce steps:

1. git clone -c core.autocrlf=true --recursive ​https://github.com/boostorg/boost.git D:\Boost\src
2. open a VS 2017 x64 command prompt and browse to D:\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\exception\test

ErrorMessage: no_exceptions_test.obj : error LNK2019: unresolved external symbol "void __cdecl boost::throw_exception(class std::exception const &,struct boost::source_location const &)" (?throw_exception@boost@@YAXAEBVexception@std@@AEBUsource_location@1@@Z) referenced in function main'

[zajo]

Should be fixed.