coccinelle: make use of the "expression" FREE_AND_NULL() rule

A follow-up to the existing "expression" rule added in an earlier
change. This manually excludes a few occurrences, mostly things that
resulted in many FREE_AND_NULL() on one line, that'll be manually
fixed in a subsequent change.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

blame.c

@@ -314,8 +314,7 @@ static void fill_origin_blob(struct diff_options *opt,
 static void drop_origin_blob(struct blame_origin *o)
 {
 	if (o->file.ptr) {
-		free(o->file.ptr);
-		o->file.ptr = NULL;
+		FREE_AND_NULL(o->file.ptr);
 	}
 }
 

ll-merge.c

@@ -209,8 +209,7 @@ static int ll_ext_merge(const struct ll_merge_driver *fn,
 	result->size = st.st_size;
 	result->ptr = xmallocz(result->size);
 	if (read_in_full(fd, result->ptr, result->size) != result->size) {
-		free(result->ptr);
-		result->ptr = NULL;
+		FREE_AND_NULL(result->ptr);
 		result->size = 0;
 	}
  close_bad: