MINOR: spoe: use pool_alloc(), not pool_alloc_dirty()

pool_alloc_dirty() is the version below pool_alloc() that never performs
the memory poisonning. It should only be called directly for very large
unstructured areas for which enabling memory poisonning would not bring
anything but could significantly hurt performance (e.g. buffers). Using
this function here will not provide any real benefit, it only avoids the
area being poisonned before being zeroed. Ideally a pool_calloc() function
should be provided for this.
diff --git a/src/flt_spoe.c b/src/flt_spoe.c
index 654f269..0397470 100644
--- a/src/flt_spoe.c
+++ b/src/flt_spoe.c
@@ -1965,7 +1965,7 @@
 	if ((appctx = appctx_new(&spoe_applet, tid_bit)) == NULL)
 		goto out_error;
 
-	appctx->ctx.spoe.ptr = pool_alloc_dirty(pool_head_spoe_appctx);
+	appctx->ctx.spoe.ptr = pool_alloc(pool_head_spoe_appctx);
 	if (SPOE_APPCTX(appctx) == NULL)
 		goto out_free_appctx;
 	memset(appctx->ctx.spoe.ptr, 0, pool_head_spoe_appctx->size);
@@ -2870,7 +2870,7 @@
 	struct spoe_config  *conf = FLT_CONF(filter);
 	struct spoe_context *ctx;
 
-	ctx = pool_alloc_dirty(pool_head_spoe_ctx);
+	ctx = pool_alloc(pool_head_spoe_ctx);
 	if (ctx == NULL) {
 		return NULL;
 	}