testsuite: Require vect_mutiple_sizes for scan-tree-dump in vect-epilogues.c

Default testsuite flags do not enable V8QI (MMX) vector mode for
32bit x86 targets.  Require vect_multiple_sizes effective target in
scan-tree-dump to avoid "LOOP EPILOGUE VECTORIZED" failure.

	* gcc.dg/vect/vect-epilogues.c (scan-tree-dump): Require
	vect_mutiple_sizes effective target.

gcc/testsuite/ChangeLog

+2020-02-21  Uroš Bizjak  <ubizjak@gmail.com>
+
+	* gcc.dg/vect/vect-epilogues.c (scan-tree-dump): Require
+	vect_mutiple_sizes effective target.
+
 2020-02-21  Jan Hubicka  <hubicka@ucw.cz>
 	    Richard Biener  <rguenther@suse.de>
 

gcc/testsuite/gcc.dg/vect/vect-epilogues.c

@@ -16,4 +16,4 @@ void pixel_avg( unsigned char *dst, int i_dst_stride,
      }
  }
 
-/* { dg-final { scan-tree-dump "LOOP EPILOGUE VECTORIZED" "vect" { xfail { arm32 && be } } } }  */
+/* { dg-final { scan-tree-dump "LOOP EPILOGUE VECTORIZED" "vect" { target vect_multiple_sizes xfail { arm32 && be } } } }  */