[PATCH 2/7] builtin/commit-graph: drop declaration for `read_replace_refs`

We have an `extern int read_replace_refs`, but that variable is not used
anymore since d24eda4e03c (repository: create disable_replace_refs(),
2023-06-06). In fact, that variable has been converted into a file-local
variable, and users are expected to call `disable_replace_refs()` now.

Remove the declaration.

Signed-off-by: Patrick Steinhardt <redacted>
---
 builtin/commit-graph.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index 415eb6afee9..14f9db5456e 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c

@@ -148,7 +148,6 @@ static int cmd_commit_graph_verify(int argc,
 	return ret;
 }
 
-extern int read_replace_refs;
 static struct commit_graph_opts write_opts;
 
 static int write_option_parse_split(const struct option *opt, const char *arg,

-- 
2.56.0.341.g393f52fd96.dirty