cleanup: add missing limits header

Add missing limits header.  Built fine without it with gcc8, etc, but
not necessarily in other environments.

Change-Id: Ib31693f04d77ad7518cfb41cc224f42d33b0ca2b
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/src/ipmiblob/blob_handler.cpp b/src/ipmiblob/blob_handler.cpp
index e5b78e1..2b79e19 100644
--- a/src/ipmiblob/blob_handler.cpp
+++ b/src/ipmiblob/blob_handler.cpp
@@ -23,6 +23,7 @@
 
 #include <array>
 #include <cstring>
+#include <limits>
 #include <memory>
 
 namespace ipmiblob