fix - use std::size_t to avoid narrowing

include/mapnik/wkb.hpp

@@ -60,7 +60,7 @@ class MAPNIK_DECL geometry_utils : private util::noncopyable
 public:
 
     static mapnik::geometry::geometry<double> from_wkb(const char* wkb,
-                                                   unsigned size,
+                                                       std::size_t size,
                                                        wkbFormat format = wkbGeneric);
 };
 

src/wkb.cpp

@@ -404,7 +404,7 @@ private:
 };
 
 mapnik::geometry::geometry<double> geometry_utils::from_wkb(const char* wkb,
-                                                        unsigned size,
+                                                            std::size_t size,
                                                             wkbFormat format)
 {
     wkb_reader reader(wkb, size, format);