use child_process_init() to initialize struct child_process variables

Call child_process_init() instead of zeroing the memory of variables of
type struct child_process by hand before use because the former is both
clearer and shorter.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

bundle.c

@@ -381,7 +381,7 @@ int create_bundle(struct bundle_header *header, const char *path,
 	write_or_die(bundle_fd, "\n", 1);
 
 	/* write pack */
-	memset(&rls, 0, sizeof(rls));
+	child_process_init(&rls);
 	argv_array_pushl(&rls.args,
 			 "pack-objects", "--all-progress-implied",
 			 "--stdout", "--thin", "--delta-base-offset",

column.c

@@ -374,7 +374,7 @@ int run_column_filter(int colopts, const struct column_options *opts)
 	if (fd_out != -1)
 		return -1;
 
-	memset(&column_process, 0, sizeof(column_process));
+	child_process_init(&column_process);
 	argv = &column_process.args;
 
 	argv_array_push(argv, "column");

trailer.c

@@ -237,7 +237,7 @@ static const char *apply_command(const char *command, const char *arg)
 		strbuf_replace(&cmd, TRAILER_ARG_STRING, arg);
 
 	argv[0] = cmd.buf;
-	memset(&cp, 0, sizeof(cp));
+	child_process_init(&cp);
 	cp.argv = argv;
 	cp.env = local_repo_env;
 	cp.no_stdin = 1;

transport-helper.c

@@ -414,7 +414,7 @@ static int get_exporter(struct transport *transport,
 	struct child_process *helper = get_helper(transport);
 	int i;
 
-	memset(fastexport, 0, sizeof(*fastexport));
+	child_process_init(fastexport);
 
 	/* we need to duplicate helper->in because we want to use it after
 	 * fastexport is done with it. */