missing alloc.h

[Steven J Abner]

machine: mac ppc G4 (1st PCI 400Mhz) OSX 10.1.5

I am trying to track a OSX bug of the definition of mode_t.
warning: passing arg 2 of `chmod' with different width due to prototype
from <sys/types.h>
        typedef u_int16_t       mode_t;
from <sys/stat.h>
        int     chmod __P((const char *, mode_t));
I downloaded coreutils for chmod code.
I used configure to obtain config.h.
checking for working alloca.h... no
checking for alloca... yes

In chmod.c      #include "system.h"
In system.h     #include <alloca.h>

If I use the makefile will it create alloca.h?
I am using project builder to create chmod for examination of the needed
size of mode_t. Apple defines 16bits. I don't actually need to install, 
but may later
use coreutils as a viable upgrade. I also note that glibc-2.3 does have 
alloc.h.
Is glibc-2.3 a prerequesite?