MINOR: stream-int: rename si_applet_{want|stop|cant}_{get|put}

It doesn't make sense to limit this code to applets, as any stream
interface can use it. Let's rename it by simply dropping the "applet_"
part of the name. No other change was made except updating the comments.
diff --git a/src/proxy.c b/src/proxy.c
index 9a6313a..f3208ef 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -1574,7 +1574,7 @@
 				bk_f_forced_id, srv_f_forced_id, srv->hostname ? srv->hostname : "-", srv->svc_port,
 				srvrecord ? srvrecord : "-");
 		if (ci_putchk(si_ic(si), &trash) == -1) {
-			si_applet_cant_put(si);
+			si_cant_put(si);
 			return 0;
 		}
 	}
@@ -1601,7 +1601,7 @@
 	if (appctx->st2 == STAT_ST_HEAD) {
 		chunk_printf(&trash, "%d\n# %s\n", SRV_STATE_FILE_VERSION, SRV_STATE_FILE_FIELD_NAMES);
 		if (ci_putchk(si_ic(si), &trash) == -1) {
-			si_applet_cant_put(si);
+			si_cant_put(si);
 			return 0;
 		}
 		appctx->st2 = STAT_ST_INFO;
@@ -1636,7 +1636,7 @@
 	if (!appctx->ctx.cli.p0) {
 		chunk_printf(&trash, "# name\n");
 		if (ci_putchk(si_ic(si), &trash) == -1) {
-			si_applet_cant_put(si);
+			si_cant_put(si);
 			return 0;
 		}
 		appctx->ctx.cli.p0 = proxies_list;
@@ -1655,7 +1655,7 @@
 
 		chunk_appendf(&trash, "%s\n", curproxy->id);
 		if (ci_putchk(si_ic(si), &trash) == -1) {
-			si_applet_cant_put(si);
+			si_cant_put(si);
 			return 0;
 		}
 	}
@@ -2148,7 +2148,7 @@
  cant_send_unlock:
 	HA_SPIN_UNLOCK(PROXY_LOCK, &appctx->ctx.errors.px->lock);
  cant_send:
-	si_applet_cant_put(si);
+	si_cant_put(si);
 	return 0;
 }