oem-ibm: Builds filetable lazily

Adds support for lid files from file table to be patched when host is
off. FileTable is rebuilt when a getFileTable request is received.

Change-Id: Ief3afb698ba4fe8b871e85c9b7c9eff1e4699daa
Signed-off-by: Rahul D S <rahulds.rahul@gmail.com>
diff --git a/oem/ibm/libpldmresponder/file_table.cpp b/oem/ibm/libpldmresponder/file_table.cpp
index 402934b..9ea1286 100644
--- a/oem/ibm/libpldmresponder/file_table.cpp
+++ b/oem/ibm/libpldmresponder/file_table.cpp
@@ -129,14 +129,21 @@
     return table;
 }
 
+/** Single instance of filetable*/
+static FileTable fileTable;
+
 FileTable& buildFileTable(const std::string& fileTablePath)
 {
-    static FileTable table;
-    if (table.isEmpty())
+    if (fileTable.isEmpty())
     {
-        table = FileTable(fileTablePath);
+        fileTable = FileTable(fileTablePath);
     }
-    return table;
+    return fileTable;
+}
+
+void clearFileTable()
+{
+    fileTable.clear();
 }
 
 } // namespace filetable