Migrate BpfInterfaceMapUpdater from U32 to S32

continuation of
  https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2184446/

replace U32 ifindex with S32

These are allocated in order by the kernel, if we go
over 2 billion, we've got other problems... besides
U32 to S32 conversion will work just fine anyway.

Bug: 245472520
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I48df3bf86f0590fbd0e21b7cf9f19d1a6bbacd31
4 files changed