Only compile wxStd{Input,Output}Stream if wxUSE_STREAMS==1.

This fixes compilation of minimal wxWidgets build.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64924 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/stdstream.cpp

@@ -20,7 +20,7 @@
     #pragma hdrstop
 #endif
 
-#if wxUSE_STD_IOSTREAM
+#if wxUSE_STREAMS && wxUSE_STD_IOSTREAM
 
 #ifndef WX_PRECOMP
 #endif
@@ -290,4 +290,4 @@ wxStdOutputStream::wxStdOutputStream(wxOutputStream& stream) :
 
 #endif // VC6/!VC6
 
-#endif // wxUSE_STD_IOSTREAM
+#endif // wxUSE_STREAMS && wxUSE_STD_IOSTREAM