Help building gdb

I've tried to build gdb 7.8 from the sources on a SLES 10 SP4 machine. 
Configure runs without error, but make stops in directory libiberty with 
the following error:

ar: ./libiberty.a: No such file or directory

The command line starts with

ar -r rc ./libiberty.a ...

Of course, with this command line ar should create rc rather than 
libiberty. I had expected the command line should read something like ar 
-rc ./libiberty.a ...

In the Makefile I see these lines:

AR = ar -r
AR_FLAGS = rc

How can this work?

What is wrong here? Do I need newer tools? make is V3.80, ar is 
V2.16.91.0.5.

Please help!

Thanks in advance!

Regards
Burkhard