iterator: cast filesystem iterator entry values explicitly

The filesystem iterator takes `stat` data from disk and puts them into
index entries, which use 32 bit ints for time (the seconds portion) and
filesize.  However, on most systems these are not 32 bit, thus will
typically invoke a warning.

Most users ignore these fields entirely.  Diff and checkout code do use
the values, however only for the cache to determine if they should check
file modification.  Thus, this is not a critical error (and will cause a
hash recomputation at worst).

src/iterator.c

@@ -1485,8 +1485,15 @@ static void filesystem_iterator_set_current(
 	filesystem_iterator *iter,
 	filesystem_iterator_entry *entry)
 {
-	iter->entry.ctime.seconds = entry->st.st_ctime;
-	iter->entry.mtime.seconds = entry->st.st_mtime;
+	/*
+	 * Index entries are limited to 32 bit timestamps.  We can safely
+	 * cast this since workdir times are only used in the cache; any
+	 * mismatch will cause a hash recomputation which is unfortunate
+	 * but affects only people who set their filetimes to 2038.
+	 * (Same with the file size.)
+	 */
+	iter->entry.ctime.seconds = (int32_t)entry->st.st_ctime;
+	iter->entry.mtime.seconds = (int32_t)entry->st.st_mtime;
 
 #if defined(GIT_USE_NSEC)
 	iter->entry.ctime.nanoseconds = entry->st.st_ctime_nsec;
@@ -1501,7 +1508,7 @@ static void filesystem_iterator_set_current(
 	iter->entry.mode = git_futils_canonical_mode(entry->st.st_mode);
 	iter->entry.uid = entry->st.st_uid;
 	iter->entry.gid = entry->st.st_gid;
-	iter->entry.file_size = entry->st.st_size;
+	iter->entry.file_size = (uint32_t)entry->st.st_size;
 
 	if (iter->base.flags & GIT_ITERATOR_INCLUDE_HASH)
 		git_oid_cpy(&iter->entry.id, &entry->id);