fix wxDFB compilation without wxUSE_LOG (#9752)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@54754 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/dfb/app.cpp

@@ -135,7 +135,9 @@ bool wxApp::Yield(bool onlyIfNeeded)
 
     s_inYield = true;
 
+#if wxUSE_LOG
     wxLog::Suspend();
+#endif // wxUSE_LOG
 
     // A guarentee that there will be an active event loop:
     wxEventLoopGuarantor dummyLoopIfNeeded;
@@ -146,7 +148,9 @@ bool wxApp::Yield(bool onlyIfNeeded)
     // OnUpdateUI() which is a nice (and desired) side effect)
     while ( ProcessIdle() ) {}
 
+#if wxUSE_LOG
     wxLog::Resume();
+#endif // wxUSE_LOG
 
     s_inYield = false;