Metis Installation Query

Hi

I would like to know what should be makefile.in for installing metis to ubuntu 10.10 x86 machine
when I tried to make using following settings
CC = gcc
OPTFLAGS = -O2
COPTIONS =
LDOPTIONS =
AR = ar rv
RANLIB = ranlib

I got following error -----------

mpiuser@node2:~/metis-4.0$ make
(cd Lib ; make )
make[1]: Entering directory `/home/mpiuser/metis-4.0/Lib'
gcc -O2 -I. -c coarsen.c
In file included from ./metis.h:36,
from coarsen.c:13:
./proto.h:462: error: conflicting types for ‘__log2’
/usr/include/bits/mathcalls.h:145: note: previous declaration of ‘__log2’ was here
make[1]: *** [coarsen.o] Error 1
make[1]: Leaving directory `/home/mpiuser/metis-4.0/Lib'
make: *** [default] Error 2

What should be these settings

COPTIONS =
LDOPTIONS =
I am new to Linux
Pls help
Thanks