tmpfile-util: turn last parameter of link_tmpfile() into a proper flags

This changes a boolean param into a proper bitflag field.

Given this only defines a single flag for now this doesn't look like
much of an improvement. But we'll add another flag shortly, where it
starts to make more sense.

src/shared/copy.c

@@ -1465,7 +1465,7 @@ int copy_file_atomic_at_full(
                         return -errno;
         }
 
-        r = link_tmpfile_at(fdt, dir_fdt, t, to, copy_flags & COPY_REPLACE);
+        r = link_tmpfile_at(fdt, dir_fdt, t, to, (copy_flags & COPY_REPLACE) ? LINK_TMPFILE_REPLACE : 0);
         if (r < 0)
                 return r;
 

src/shared/hwdb-util.c

@@ -408,7 +408,7 @@ static int trie_store(struct trie *trie, const char *filename, bool compat) {
                 return -errno;
         fwrite(&h, sizeof(struct trie_header_f), 1, f);
 
-        r = flink_tmpfile(f, filename_tmp, filename, /* replace= */ true);
+        r = flink_tmpfile(f, filename_tmp, filename, LINK_TMPFILE_REPLACE);
         if (r < 0)
                 return r;