update clean command for BSD

Makefile.FreeBSD

@@ -28,7 +28,7 @@ OBJSUFFICS = .o
 DEFINEOPTION = -D
 COMPFILES = *~
 REMOVECOMMAND = rm -f
-AFTERCLEAN = find src/ -type f -name "*.o" -delete && find src/ -type f -name "Makefile.var" -delete && find bin/ -type f -executable -delete
+AFTERCLEAN = find src/ -type f -name "*.o" -delete && find src/ -type f -name "Makefile.var" -delete && find bin/ -type f -perm +111 -delete
 TYPECOMMAND = cat
 COMPATLIBS =
 MAKEFILE = Makefile.FreeBSD