Minor regression with toolset v141_xp (Visual Studio 2017 - Windows XP)

[thebrandre]

Before boost version 1.83 and commit 32dbf1b it was possible to compile for Windows XP by setting just the one define define=BOOST_USE_WINAPI_VERSION=0x0501 as an argument for b2.

Now it is also required to add define=_USING_V110_SDK71_. Otherwise you'll get a linker error:

msvcprt.lib(sharedmutex.obj) : error LNK2019: unresolved external symbol __imp_ReleaseSRWLockExclusive referenced in function _Smtx_unlock_exclusive
msvcprt.lib(sharedmutex.obj) : error LNK2019: unresolved external symbol __imp_ReleaseSRWLockShared referenced in function _Smtx_unlock_shared
msvcprt.lib(sharedmutex.obj) : error LNK2019: unresolved external symbol __imp_AcquireSRWLockExclusive referenced in function _Smtx_lock_exclusive
msvcprt.lib(sharedmutex.obj) : error LNK2019: unresolved external symbol __imp_AcquireSRWLockShared referenced in function _Smtx_lock_shared
msvcprt.lib(sharedmutex.obj) : error LNK2019: unresolved external symbol __imp_TryAcquireSRWLockExclusive referenced in function _Smtx_try_lock_exclusive
msvcprt.lib(sharedmutex.obj) : error LNK2019: unresolved external symbol __imp_TryAcquireSRWLockShared referenced in function _Smtx_try_lock_shared

It is not a big deal because we should have been adding this define all along. So there is not actually a need for action here and you can simply close the issue.
I just wanted to point it out in case anyone has a similar problem because, unfortunately, this was not quite so easy to trace back.

[pdimov]

A similar problem has been reported in #113 and the fix a57c568 should make this no longer an issue, even though defining _USING_V110_SDK71_ is still a good idea.