trace.c, git.c: remove unnecessary parameter to trace_repo_setup()

trace_repo_setup() of trace.c is called with the argument 'prefix' from
only one location, run_builtin of git.c, which sets 'prefix' to the return
value of setup_git_directory() or setup_git_directory_gently() (a wrapper
of the former).

Now that "prefix" is in startup_info there is no need for the parameter
of trace_repo_setup() because setup_git_directory() sets "startup_info->prefix"
to the same value it returns. It would be less confusing to use "prefix"
from startup_info instead of passing it as an argument.

Signed-off-by: Idriss Fekir <mcsm224@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git.c

@@ -430,7 +430,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 		use_pager = 1;
 	if (run_setup && startup_info->have_repository)
 		/* get_git_dir() may set up repo, avoid that */
-		trace_repo_setup(prefix);
+		trace_repo_setup();
 	commit_pager_choice();
 
 	if (!help && p->option & NEED_WORK_TREE)

trace.c

@@ -291,10 +291,9 @@ static const char *quote_crnl(const char *path)
 	return new_path.buf;
 }
 
-/* FIXME: move prefix to startup_info struct and get rid of this arg */
-void trace_repo_setup(const char *prefix)
+void trace_repo_setup(void)
 {
-	const char *git_work_tree;
+	const char *git_work_tree, *prefix = startup_info->prefix;
 	char *cwd;
 
 	if (!trace_want(&trace_setup_key))
@@ -305,7 +304,7 @@ void trace_repo_setup(const char *prefix)
 	if (!(git_work_tree = get_git_work_tree()))
 		git_work_tree = "(null)";
 
-	if (!prefix)
+	if (!startup_info->prefix)
 		prefix = "(null)";
 
 	trace_printf_key(&trace_setup_key, "setup: git_dir: %s\n", quote_crnl(get_git_dir()));

trace.h

@@ -93,7 +93,7 @@ extern struct trace_key trace_default_key;
 extern struct trace_key trace_perf_key;
 extern struct trace_key trace_setup_key;
 
-void trace_repo_setup(const char *prefix);
+void trace_repo_setup(void);
 
 /**
  * Checks whether the trace key is enabled. Used to prevent expensive