Forward declare wavelet_decomposition

rtengine/cplx_wavelet_dec.h

@@ -17,9 +17,7 @@
  *  2010 Ilya Popov <ilia_popov@rambler.ru>
  *  2012 Emil Martinec <ejmartin@uchicago.edu>
  */
-
-#ifndef CPLX_WAVELET_DEC_H_INCLUDED
-#define CPLX_WAVELET_DEC_H_INCLUDED
+#pragma once
 
 #include <cstddef>
 #include <cmath>
@@ -266,5 +264,3 @@ void wavelet_decomposition::reconstruct(E * dst, const float blend)
 }
 
 }
-
-#endif