[master] Removed test for PNG_CONFIGURE_LIBPNG from pngconf.h

pngconf.h

@@ -1534,7 +1534,7 @@ typedef z_stream FAR *  png_zstreamp;
  * functions in png.h will generate compiler warnings.  Added at libpng
  * version 1.2.41.
  */
-#ifdef __GNUC__
+#  ifdef __GNUC__
 #    ifndef PNG_USE_RESULT
 #      define PNG_USE_RESULT __attribute__((__warn_unused_result__))
 #    endif
@@ -1545,7 +1545,6 @@ typedef z_stream FAR *  png_zstreamp;
 #      define PNG_ALLOCATED  __attribute__((__malloc__))
 #    endif
 
-#  ifndef PNG_CONFIGURE_LIBPNG
     /* This specifically protects structure members that should only be
      * accessed from within the library, therefore should be empty during
      * a library build.
@@ -1557,16 +1556,15 @@ typedef z_stream FAR *  png_zstreamp;
 #      define PNG_DEPSTRUCT  __attribute__((__deprecated__))
 #    endif
 #    ifndef PNG_PRIVATE
-#if 0 /* Doesn't work so we use deprecated instead*/
+#      if 0 /* Doesn't work so we use deprecated instead*/
 #        define PNG_PRIVATE \
           __attribute__((warning("This function is not exported by libpng.")))
-#else
+#      else
 #        define PNG_PRIVATE \
           __attribute__((__deprecated__))
-#endif
 #      endif
-#  endif
-#endif
+#    endif /* PNG_PRIVATE */
+#  endif /* __GNUC__ */
 #endif /* PNG_PEDANTIC_WARNINGS */
 
 #ifndef PNG_DEPRECATED