add headers to the samples' bakefiles so that they show up in MSVC project files

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@59311 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/opengl/cube/cube.bkl

@@ -11,6 +11,7 @@
 
     <exe id="cube" template="wx_sample" template_append="wx_append" cond="USE_OPENGL=='1'">
         <sources>cube.cpp</sources>
+        <headers>cube.h</headers>
         <wx-lib>gl</wx-lib>
         <wx-lib>core</wx-lib>
         <wx-lib>base</wx-lib>

samples/opengl/isosurf/isosurf.bkl

@@ -11,6 +11,7 @@
 
     <exe id="isosurf" template="wx_sample" template_append="wx_append" cond="USE_OPENGL=='1'">
         <sources>isosurf.cpp</sources>
+        <headers>isosurf.h</headers>
         <wx-lib>gl</wx-lib>
         <wx-lib>core</wx-lib>
         <wx-lib>base</wx-lib>

samples/opengl/penguin/penguin.bkl

@@ -4,7 +4,7 @@
 <makefile>
 
     <include file="../../../build/bakefiles/common_samples.bkl"/>
-    
+
     <if cond="OUT_OF_TREE_MAKEFILES=='1'">
         <set var="USE_OPENGL">1</set>
     </if>
@@ -15,6 +15,11 @@
             dxfrenderer.cpp
             trackball.c
         </sources>
+        <headers>
+            dxfrenderer.h
+            penguin.h
+            trackball.h
+        </headers>
         <wx-lib>gl</wx-lib>
         <wx-lib>core</wx-lib>
         <wx-lib>base</wx-lib>