Fix build with OpenEXR>=3

Index: src-IL/include/il_exr.h
--- src-IL/include/il_exr.h.orig
+++ src-IL/include/il_exr.h
@@ -63,8 +63,8 @@ class ilIStream : public Imf::IStream
 		virtual bool	read (char c[/*n*/], int n);
 		// I don't think I need this one, since we are taking care of the file handles ourselves.
 		//virtual char *	readMemoryMapped (int n);
-		virtual Imf::Int64	tellg ();
-		virtual void	seekg (Imf::Int64 Pos);
+		virtual uint64_t	tellg ();
+		virtual void	seekg (uint64_t Pos);
 		virtual void	clear ();
 
 	protected:
@@ -79,8 +79,8 @@ class ilOStream : public Imf::OStream
 		virtual void	write (const char c[/*n*/], int n);
 		// I don't think I need this one, since we are taking care of the file handles ourselves.
 		//virtual char *	readMemoryMapped (int n);
-		virtual Imf::Int64	tellp ();
-		virtual void	seekp (Imf::Int64 Pos);
+		virtual uint64_t	tellp ();
+		virtual void	seekp (uint64_t Pos);
 
 	protected: