flashmap: Fix warnings with gcc 10

BUG=b:229038573
TEST=ran unittests

Change-Id: I3a3c428c4c2a9eba6d1ff353e712f1220d5728cf
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/flashmap/+/4601333
Reviewed-by: Jack Rosenthal <[email protected]>
Tested-by: Dmitry Bilunov <[email protected]>
Commit-Queue: Dmitry Bilunov <[email protected]>
1 file changed