mailconfig UI: prefilled username: only clear when disabled.

logic error - the username was being cleared on initial page load,
and was toggling on and off every time the radio button was tapped.

Change-Id: I8c2334665cd18fe8cdd0ea6739e90b088a105256
Reviewed-on: https://gerrit.libreoffice.org/49467Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Justin Luth <justin_luth@sil.org>

sw/source/ui/config/mailconfigpage.cxx

@@ -517,12 +517,12 @@ IMPL_LINK_NOARG(SwAuthenticationSettingsDialog, RadioButtonHdl_Impl, Button*, vo
 
     if ( bSeparate && m_pUserNameED->GetText().isEmpty() )
         m_pUserNameED->SetText( rConfigItem.GetMailAddress() );
-    else if ( m_pUserNameED->GetText() == rConfigItem.GetMailAddress() )
+    else if ( !bSeparate && m_pUserNameED->GetText() == rConfigItem.GetMailAddress() )
         m_pUserNameED->SetText("");
 
     if ( bNotSeparate && m_pInUsernameED->GetText().isEmpty() )
         m_pInUsernameED->SetText( rConfigItem.GetMailAddress() );
-    else if ( m_pInUsernameED->GetText() == rConfigItem.GetMailAddress() )
+    else if ( !bNotSeparate && m_pInUsernameED->GetText() == rConfigItem.GetMailAddress() )
         m_pInUsernameED->SetText("");
 
     m_pOutgoingServerFT->Enable(bSeparate);