conversion to grey16 could lock

a typo could cause infinite recursion during conversion

ChangeLog

@@ -13,6 +13,7 @@
 - autorotate option for tiff load
 - tiffsave converts for jpg if jpg compression is turned on
 - tiffsave supports --strip
+- conversions to GREY16 could lock
 
 18/5/16 started 8.3.2
 - more robust vips image reading

libvips/colour/colourspace.c

@@ -79,7 +79,7 @@ vips_scRGB2RGB16( VipsImage *in, VipsImage **out, ... )
 static int
 vips_scRGB2BW16( VipsImage *in, VipsImage **out, ... )
 {
-	return( vips_scRGB2BW16( in, out, "depth", 16, NULL ) );
+	return( vips_scRGB2BW( in, out, "depth", 16, NULL ) );
 }
 
 /* Do these two with a simple cast ... since we're just cast shifting, we can