regressions/ck_ring: Allow for buffers of size 4 or more.

regressions/ck_ring/validate/ck_ring_spmc.c

@@ -241,7 +241,7 @@ main(int argc, char *argv[])
 	assert(nthr >= 1);
 
 	size = atoi(argv[3]);
-	assert(size > 4 && (size & size - 1) == 0);
+	assert(size >= 4 && (size & size - 1) == 0);
 	size -= 1;
 
 	ring = malloc(sizeof(ck_ring_t) * nthr);

regressions/ck_ring/validate/ck_ring_spmc_template.c

@@ -214,7 +214,7 @@ main(int argc, char *argv[])
 	assert(nthr >= 1);
 
 	size = atoi(argv[3]);
-	assert(size > 4 && (size & size - 1) == 0);
+	assert(size >= 4 && (size & size - 1) == 0);
 	size -= 1;
 
 	ring = malloc(sizeof(ck_ring_t) * nthr);

regressions/ck_ring/validate/ck_ring_spsc.c

@@ -166,7 +166,7 @@ main(int argc, char *argv[])
 	assert(nthr >= 1);
 
 	size = atoi(argv[3]);
-	assert(size > 4 && (size & size - 1) == 0);
+	assert(size >= 4 && (size & size - 1) == 0);
 	size -= 1;
 
 	ring = malloc(sizeof(ck_ring_t) * nthr);

regressions/ck_ring/validate/ck_ring_spsc_template.c

@@ -167,7 +167,7 @@ main(int argc, char *argv[])
 	assert(nthr >= 1);
 
 	size = atoi(argv[3]);
-	assert(size > 4 && (size & size - 1) == 0);
+	assert(size >= 4 && (size & size - 1) == 0);
 	size -= 1;
 
 	ring = malloc(sizeof(CK_RING_INSTANCE(entry_ring)) * nthr);