Commit 07eea3aa4 `make --shuffle` prevented shuffling prerequisites
that use .SECONDEXPANSION, since shuffle happens before expansion.
This has two problems:
1. No shuffling happens for such prerequisites.
2. Use-after-free when outdated '->shuf' links are used.
Add a reshuffle into expansion phase right after dependency changes.
* src/file.c (expand_deps): Add reshuffle if dependencies change.
* src/shuffle.c (identity_shuffle_array): Fix comment typo.
* tests/scripts/options/shuffle: Add new SECONDEXPANSION test.
ca4234c4b5