BUG/MINOR: stats: Add a missing break in a switch statement

A break is missing in the switch statement in the function
stats_emit_json_data_field(). This bug was introduced in the commit 88a0db28a
("MINOR: stats: Add the support of float fields in stats").

This patch fixes the issue #302 and #303. It must be backported to 2.0.
diff --git a/src/stats.c b/src/stats.c
index f280e5a..5a0d4e1 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -391,6 +391,7 @@
 		       type = "\"u64\"";
 		       snprintf(buf, sizeof(buf), "%llu",
 				(unsigned long long) f->u.u64);
+		       break;
 	case FF_FLT:   type = "\"flt\"";
 		       snprintf(buf, sizeof(buf), "%f", f->u.flt);
 		       break;