reftable/writer: drop static variable used to initialize strbuf

We have a static variable in the reftable writer code that is merely
used to initialize the `last_key` of the writer. Convert the code to
instead use `strbuf_init()` and drop the variable.

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

Author: pks-t

reftable/writer.c

@@ -117,8 +117,6 @@ static void writer_reinit_block_writer(struct reftable_writer *w, uint8_t typ)
 	w->block_writer->restart_interval = w->opts.restart_interval;
 }
 
-static struct strbuf reftable_empty_strbuf = STRBUF_INIT;
-
 struct reftable_writer *
 reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
 		    int (*flush_func)(void *),
@@ -136,7 +134,7 @@ reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
 	}
 
 	strbuf_init(&wp->block_writer_data.last_key, 0);
-	wp->last_key = reftable_empty_strbuf;
+	strbuf_init(&wp->last_key, 0);
 	REFTABLE_CALLOC_ARRAY(wp->block, opts.block_size);
 	wp->write = writer_func;
 	wp->write_arg = writer_arg;