Enable readability-container-size-empty tests

This one is a little trivial, but it does help in readability.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I5366d4eec8af2f781b3bad804131ae2eb806e3aa
diff --git a/include/ibm/locks.hpp b/include/ibm/locks.hpp
index 5a86d09..45525bf 100644
--- a/include/ibm/locks.hpp
+++ b/include/ibm/locks.hpp
@@ -299,7 +299,7 @@
         auto it = lockTable.begin();
         while (it != lockTable.end())
         {
-            if (it->second.size() != 0)
+            if (!it->second.empty())
             {
                 // Check if session id of this entry matches with session id
                 // given