move boost header dependency for ControlCacheHashFunction inside vcl

ControlCacheHashFunction is only used by vcl/opengl/*

Change-Id: Id3aef4fc1ffc909a24a9cce0b86c5dc82e6e6612
Reviewed-on: https://gerrit.libreoffice.org/21900Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

include/vcl/salnativewidgets.hxx

@@ -25,8 +25,6 @@
 #include <tools/gen.hxx>
 #include <o3tl/typed_flags_set.hxx>
 
-#include <boost/functional/hash.hpp>
-
 /* Control Types:
  *
  *   Specify the overall, whole control
@@ -302,21 +300,6 @@ public:
     }
 };
 
-struct ControlCacheHashFunction
-{
-    std::size_t operator()(ControlCacheKey const& aCache) const
-    {
-        std::size_t seed = 0;
-        boost::hash_combine(seed, aCache.mnType);
-        boost::hash_combine(seed, aCache.mnPart);
-        boost::hash_combine(seed, aCache.mnState);
-        boost::hash_combine(seed, aCache.maSize.Width());
-        boost::hash_combine(seed, aCache.maSize.Height());
-        return seed;
-    }
-};
-
-
 /* ButtonValue:
  *
  *   Identifies the tri-state value options

vcl/inc/svdata.hxx

@@ -34,6 +34,7 @@
 #include "xconnection.hxx"
 
 #include <unordered_map>
+#include <boost/functional/hash.hpp>
 
 struct ImplTimerData;
 struct ImplIdleData;
@@ -399,6 +400,20 @@ struct ImplSVEvent
     bool                mbCall;
 };
 
+struct ControlCacheHashFunction
+{
+    std::size_t operator()(ControlCacheKey const& aCache) const
+    {
+        std::size_t seed = 0;
+        boost::hash_combine(seed, aCache.mnType);
+        boost::hash_combine(seed, aCache.mnPart);
+        boost::hash_combine(seed, aCache.mnState);
+        boost::hash_combine(seed, aCache.maSize.Width());
+        boost::hash_combine(seed, aCache.maSize.Height());
+        return seed;
+    }
+};
+
 #endif // INCLUDED_VCL_INC_SVDATA_HXX
 
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