fast-import: die_nicely() back to vsnprintf (reverts part of ebaa79f)

ebaa79f (Make report() from usage.c public as vreportf() and use it.,
2010-03-06) changed fast-import's die_nicely() to use vreportf().
Unfortunately this is not possible: we need the message again for
write_report(), and vreportf() uses vsnprintf(), which invalidates the
va_list.  As pointed out by Erik Faye-Lund, va_copy is C99 and thus
not an option.

So revert the part of ebaa79f that pertains to die_nicely().

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fast-import.c

@@ -483,12 +483,14 @@ static void dump_marks(void);
 static NORETURN void die_nicely(const char *err, va_list params)
 {
 	static int zombie;
+	char message[2 * PATH_MAX];
 
-	vreportf("fatal: ", err, params);
+	vsnprintf(message, sizeof(message), err, params);
+	fputs("fatal: ", stderr);
+	fputs(message, stderr);
+	fputc('\n', stderr);
 
 	if (!zombie) {
-		char message[2 * PATH_MAX];
-
 		zombie = 1;
 		write_crash_report(message);
 		end_packfile();