sparse-index: correctly free EWAH contents

While we free the `fsmonitor_dirty` member of `struct index_state`, we
do not free the contents of that EWAH. Do so by using `ewah_free()`
instead of `FREE_AND_NULL()`.

This leak is exposed by t7519, but plugging it alone does not make the
test suite pass.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

sparse-index.c

@@ -2,6 +2,7 @@
 
 #include "git-compat-util.h"
 #include "environment.h"
+#include "ewah/ewok.h"
 #include "gettext.h"
 #include "name-hash.h"
 #include "read-cache-ll.h"
@@ -242,7 +243,8 @@ int convert_to_sparse(struct index_state *istate, int flags)
 	cache_tree_update(istate, 0);
 
 	istate->fsmonitor_has_run_once = 0;
-	FREE_AND_NULL(istate->fsmonitor_dirty);
+	ewah_free(istate->fsmonitor_dirty);
+	istate->fsmonitor_dirty = NULL;
 	FREE_AND_NULL(istate->fsmonitor_last_update);
 
 	istate->sparse_index = INDEX_COLLAPSED;
@@ -438,7 +440,8 @@ void expand_index(struct index_state *istate, struct pattern_list *pl)
 	istate->cache_nr = full->cache_nr;
 	istate->cache_alloc = full->cache_alloc;
 	istate->fsmonitor_has_run_once = 0;
-	FREE_AND_NULL(istate->fsmonitor_dirty);
+	ewah_free(istate->fsmonitor_dirty);
+	istate->fsmonitor_dirty = NULL;
 	FREE_AND_NULL(istate->fsmonitor_last_update);
 
 	strbuf_release(&base);