Default nmaximpl to 4 instead of 8, as iterating over implementations is very costly

configure.ac

@@ -1703,7 +1703,7 @@ AC_DEFINE_UNQUOTED(STARPU_NMAX_COMBINEDWORKERS,
 AC_MSG_CHECKING(maximum number of implementations)
 AC_ARG_ENABLE(maximplementations, [AS_HELP_STRING([--enable-maximplementations=<number>],
 		[maximum number of implementations])],
-		maximplementations=$enableval, maximplementations=8)
+		maximplementations=$enableval, maximplementations=4)
 AC_MSG_RESULT($maximplementations)
 AC_DEFINE_UNQUOTED(STARPU_MAXIMPLEMENTATIONS, [$maximplementations],
 		[maximum number of implementations])

examples/basic_examples/vector_scal.c

@@ -65,7 +65,6 @@ static struct starpu_codelet cl =
 		, scal_sse_func_icc
 #endif
 #endif
-		, NULL
 	},
 	.cpu_funcs_name = {
 		"scal_cpu_func",