Add overflow flag checking

This is to ensure that we check for and flag buffer overflow flag from
the BIOS.

The logic should be:

```
1. BIOS_switch ^ BMC_switch == 0 → No overflow incident
  a. CONTINUE
2. BIOS_switch ^ BMC_switch == 1 → an unlogged overflow incident has occurred
  b. Log the overflow incident
  c. Toggle the BMC overflow flag
```

Tested: Added unit test

Signed-off-by: Brandon Kim <brandonkim@google.com>
Change-Id: I25c50a8de93900480413389d7d2a89b9be4b5643
diff --git a/src/main.cpp b/src/main.cpp
index 4465185..eb15677 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -79,6 +79,13 @@
             bufferInterface->updateBmcFlags(newBmcFlags);
         }
 
+        if (bufferInterface->checkForOverflowAndAcknowledge())
+        {
+            stdplus::print(
+                stdout,
+                "[WARN] Buffer overflow had occured and has been acked\n");
+        }
+
         std::vector<EntryPair> entryPairs = bufferInterface->readErrorLogs();
         for (const auto& [entryHeader, entry] : entryPairs)
         {