fsmonitor: check CE_FSMONITOR_VALID in ce_uptodate

When using fsmonitor the CE_FSMONITOR_VALID flag should be checked when
wanting to know if the entry has been updated. If the flag is set the
entry should be considered up to date and the same as if the CE_UPTODATE
is set.

In order to trust the CE_FSMONITOR_VALID flag, the fsmonitor data needs to
be refreshed when the fsmonitor bitmap is applied to the index in
tweak_fsmonitor. Since the fsmonitor data is kept up to date for every
command, some tests needed to be updated to take that into account.

istate->untracked->use_fsmonitor was set in tweak_fsmonitor when the
fsmonitor bitmap data was loaded and is now in refresh_fsmonitor since
that is being called in tweak_fsmonitor. refresh_fsmonitor will only be
called once and any other callers should be setting it when refreshing
the fsmonitor data so that code can use the fsmonitor data when checking
untracked files.

When writing the index, fsmonitor_last_update is used to determine if
the fsmonitor bitmap should be created and the extension data written to
the index. When running through unpack-trees this is not copied to the
result index. This makes the next time a git command is ran do all the
work of lstating all files to determine what is clean since all entries
in the index are marked as dirty since there wasn't any fsmonitor data
saved in the index extension.

Copying the fsmonitor_last_update to the result index will cause the
extension data for fsmonitor to be in the index for the next git command
to use.

Signed-off-by: Kevin Willford <Kevin.Willford@microsoft.com>

read-cache-ll.h

@@ -118,7 +118,7 @@ static inline unsigned create_ce_flags(unsigned stage)
 #define ce_namelen(ce) ((ce)->ce_namelen)
 #define ce_size(ce) cache_entry_size(ce_namelen(ce))
 #define ce_stage(ce) ((CE_STAGEMASK & (ce)->ce_flags) >> CE_STAGESHIFT)
-#define ce_uptodate(ce) ((ce)->ce_flags & CE_UPTODATE)
+#define ce_uptodate(ce) (((ce)->ce_flags & CE_UPTODATE) || ((ce)->ce_flags & CE_FSMONITOR_VALID))
 #define ce_skip_worktree(ce) ((ce)->ce_flags & CE_SKIP_WORKTREE)
 #define ce_mark_uptodate(ce) ((ce)->ce_flags |= CE_UPTODATE)
 #define ce_intent_to_add(ce) ((ce)->ce_flags & CE_INTENT_TO_ADD)