Fix incorrect override of GetLayoutOrder().

Fix incorrect override of GetLayoutOrder().

fsdk_baseform.h:63:19: error: 'CPDFSDK_Widget::GetLayoutOrder' hides overloaded virtual function [-Werror,-Woverloaded-virtual]
        virtual int                                             GetLayoutOrder() {return 2;}
                                                                ^
fsdk_baseannot.h:70:18: note: hidden overloaded virtual function 'CPDFSDK_Annot::GetLayoutOrder' declared here: different qualifiers (const vs none)
        virtual int                                     GetLayoutOrder() const { return 5; }
                                                        ^

On Windows, I believe MSVS treats these as override since it's such a common and
easy mistake, but clang and gcc do what the standard specifies. Add a "const" to
the function in the subclass so that this is actually an override, as intended.

BUG=pdfium:29
R=bo_xu@foxitsoftware.com

Committed: https://pdfium.googlesource.com/pdfium/+/fe08482

[Bo Xu, 2014-07-30 21:15:08]

On 2014/07/30 01:30:35, Nico (away) wrote:

lgtm

[Nico, 2014-07-30 21:16:38]

Committed patchset #1 manually as rfe08482 (presubmit successful).