builtin_target.c: Fix AVX-512VBMI detection.

gcc/testsuite/
	* gcc.target/i386/builtin_target.c: Fix AVX-512VBMI detection.

From-SVN: r228515

gcc/testsuite/gcc.target/i386/builtin_target.c

@@ -211,7 +211,7 @@ check_features (unsigned int ecx, unsigned int edx,
 	assert (__builtin_cpu_supports ("avx512dq"));
       if (ebx & bit_AVX512IFMA)
 	assert (__builtin_cpu_supports ("avx512ifma"));
-      if (ebx & bit_AVX512VBMI)
+      if (ecx & bit_AVX512VBMI)
 	assert (__builtin_cpu_supports ("avx512vbmi"));
     }
 }