Frameworks/base: Fix two warnings in cmds

Change-Id: Ifb9c7fb7a2d28c13010ddc186bea5f5f0daefb4a
diff --git a/cmds/idmap/create.cpp b/cmds/idmap/create.cpp
index 28da3d6..7a501a4 100644
--- a/cmds/idmap/create.cpp
+++ b/cmds/idmap/create.cpp
@@ -78,7 +78,7 @@
         if (fstat(idmap_fd, &st) == -1) {
             return true;
         }
-        if (st.st_size < N) {
+        if (st.st_size < static_cast<off_t>(N)) {
             // file is empty or corrupt
             return true;
         }