fixdep: remove unneeded <stdarg.h> inclusion

This is unneeded since commit 69304379ff ("fixdep: use fflush() and
ferror() to ensure successful write to files").

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/basic/fixdep.c

@@ -94,7 +94,6 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <string.h>
-#include <stdarg.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <ctype.h>