Prevent GTK printing build error on Linux

* Do not fail to build when wxWidgets is built with either --with-gnomeprint
  or --with-gtkprint are not configured.  Only display warning.
* Move warning code from include/common.h to common/common.cpp so it only
  shows the warning once instead of every source file that includes common.h

common/common.cpp

@@ -40,6 +40,20 @@
 
 #include <wx/process.h>
 
+
+// Fail build if wxWidgets printing was not configured.
+#if !wxUSE_PRINTING_ARCHITECTURE && !SWIG
+#   error "You must use '--enable-printarch' in your wx library configuration."
+#endif
+
+// Show warning if wxWidgets Gnome or GTK printing was not configured.
+#if defined( __WXGTK__ )
+#   if !wxUSE_LIBGNOMEPRINT && !wxUSE_GTKPRINT && !SWIG
+#       warning "You must use '--with-gnomeprint' or '--with-gtkprint' in your wx library configuration for full print capabilities."
+#   endif
+#endif
+
+
 /**
  * Global variables definitions.
  *

include/common.h

@@ -42,16 +42,6 @@
 #include <convert_to_biu.h>
 #include <colors.h>
 
-#if !wxUSE_PRINTING_ARCHITECTURE && !SWIG
-#   error "You must use '--enable-printarch' in your wx library configuration."
-#endif
-
-#if defined( __WXGTK__ )
-#   if !wxUSE_LIBGNOMEPRINT && !wxUSE_GTKPRINT && !SWIG
-#       error "You must use '--with-gnomeprint' or '--with-gtkprint' in your wx library configuration."
-#   endif
-#endif
-
 
 class wxAboutDialogInfo;