fixed typo: _() was used instead of _T()

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_4_BRANCH@17762 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/thread.cpp

@@ -243,7 +243,7 @@ wxMutexError wxMutexInternal::Unlock()
 {
     if ( !::ReleaseMutex(m_mutex) )
     {
-        wxLogLastError(_("ReleaseMutex()"));
+        wxLogLastError(_T("ReleaseMutex()"));
 
         return wxMUTEX_MISC_ERROR;
     }