Add changelog entry for 3.0.3.1

Add back the old method name, replacing it with SetInnerSizer() in
6b335c8ca4 wasn't ABI (nor even API) compatible.

Still keep SetInnerSizer() and do _not_ add it to version-script.in to avoid
breaking compatibility with 3.0.3 now.

Closes #17861.

docs/changes.txt

@@ -580,6 +580,13 @@ Major new features in this release
 
 
 
+3.0.3.1: (released 2017-05-15)
+------------------------------
+
+Bug fix release adding back wxPropertySheetDialog::SetInnerSize() mistakenly
+removed in 3.0.3. There are no other changes in this micro-release.
+
+
 3.0.3: (released 2017-05-02)
 ----------------------------
 

include/wx/generic/propdlg.h

@@ -109,7 +109,12 @@ public:
     virtual wxWindow* GetContentWindow() const;
 
     // Set and get the inner sizer
+
+    // Keep old version with a typo in it for ABI compatibility.
+    void SetInnerSize(wxSizer* sizer) { m_innerSizer = sizer; }
+#if wxABI_VERSION >= 30003
     void SetInnerSizer(wxSizer* sizer) { m_innerSizer = sizer; }
+#endif
     wxSizer* GetInnerSizer() const { return m_innerSizer ; }
 
     // Set and get the book style