Merge in change from gnulib.

Remove block of alloca-related code in favor
of an unconditional `#include <alloca.h>'.

lib/makepath.c

@@ -1,6 +1,7 @@
 /* makepath.c -- Ensure that a directory path exists.
-   Copyright (C) 1990, 1997, 1998, 1999, 2000, 2002, 2003 Free Software
-   Foundation, Inc.
+
+   Copyright (C) 1990, 1997, 1998, 1999, 2000, 2002, 2003 Free
+   Software Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -22,19 +23,7 @@
 # include <config.h>
 #endif
 
-#if __GNUC__
-# define alloca __builtin_alloca
-#else
-# if HAVE_ALLOCA_H
-#  include <alloca.h>
-# else
-#  ifdef _AIX
- #  pragma alloca
-#  else
-char *alloca ();
-#  endif
-# endif
-#endif
+#include <alloca.h>
 
 #include <stdio.h>
 #include <sys/types.h>