SalGtk{File,}Picker.hxx: Add missing includes

Since 'XComponentContext' and 'DECL_STATIC_LINK' are used,
add the corresponding includes.

Otherwise a successful build depends on the header being
included after other headers that make sure that compilation
still works.

An error could be provoked e.g. by moving the
'#include <gtk/fpicker/SalGtkFilePicker.hxx>' in
'vcl/unx/gtk/fpicker/SalGtkFilePicker.cxx' above all
other existing includes.

Change-Id: Ib23f8b714fb971238eab28a8d4d02414a0b13812
Reviewed-on: https://gerrit.libreoffice.org/65208
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

vcl/unx/gtk/fpicker/SalGtkFilePicker.hxx

@@ -25,6 +25,7 @@
 #include <com/sun/star/ui/dialogs/XFilePickerControlAccess.hpp>
 #include <com/sun/star/ui/dialogs/XFilePreview.hpp>
 #include <com/sun/star/ui/dialogs/XFilePicker3.hpp>
+#include <com/sun/star/uno/XComponentContext.hpp>
 #include <com/sun/star/beans/StringPair.hpp>
 
 #include <vector>

vcl/unx/gtk/fpicker/SalGtkPicker.hxx

@@ -21,12 +21,14 @@
 #define INCLUDED_VCL_UNX_GTK_FPICKER_SALGTKPICKER_HXX
 
 #include <osl/mutex.hxx>
+#include <tools/link.hxx>
 #include <cppuhelper/compbase.hxx>
 
 #include <com/sun/star/awt/XTopWindowListener.hpp>
 #include <com/sun/star/awt/XExtendedToolkit.hpp>
 #include <com/sun/star/frame/XDesktop.hpp>
 #include <com/sun/star/frame/XTerminateListener.hpp>
+#include <com/sun/star/uno/XComponentContext.hpp>
 
 #include <gtk/gtk.h>
 #include <gdk/gdkkeysyms.h>