undefined reference to 'system'

[Joachim Mammele <mail@jomammele.de>]

Hi everybody,
I have got a tablet with special frontkeys and I would like to install 
and adapt android on it. This works fine with the project android-x86.org

On grub I would like to select the bootitems with the frontkeys.
The frontkeys can be read with the following code (this is working,
file named readFrontKey.c).
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/io.h>
int main()
{
   unsigned char bits8, bits9, bits0, bitsA, bitsB, bitsC, bitsD,
bitsE, bits;
   if(ioperm(0x208, 8, 1) < 0) {
         perror("0x208");
         return 1;
   }
         bits = 32;
         outb(bits, 0x20A);
         outw(-16832, 0x20C);
         bits9 = inb(0x209);
         return bits9;
}
But when I add the following code to external/grub/stage2/stage2.c I get an
"undefined reference to `system' " error message:

The code I added to stage2.c (at roundabout line 391) is
bits9 = system("readFrontKey");
           if (bits9 == 64)
                 entryno = 1;
           if (bits9 == 32)
                 entryno = 2;
           if (bits9 == 16)
             entryno = 3;
           goto boot_entry;
       /* Check for a keypress, however if TIMEOUT has been expired
          (GRUB_TIMEOUT == -1) relax in GETKEY even if no key has been
          pressed.

stage2.c has stdlib.h included.

I added the program readfrontkey.c to Makefile.am and also adapted
Makefile.in
Any help woud be apreciated
Joachim Mammele

P.S. The repository that I use can be found here: 
http://android-x86.git.sourceforge.net/git/gitweb.cgi?p=android-x86/korg_external_grub.git;a=summary