Problem compiling on CentOS

Hi,

I'm trying to recompile the SRPM with ldap support (maybe this should
be added as an option to the spec?) but it fails to check for ldap_r
due to problems finding my pthread flag in configure.

Snip from configure:
checking whether pthreads work with -pthread... no
...
checking for ldap_simple_bind in -lldap_r... no
configure: error: library 'ldap_r' is required for LDAP

checking the log for why pthread failed:
configure:16390: checking whether pthreads work with -pthread
configure:16478: gcc -o conftest -O2 -g -march=i386 -mcpu=i686
-I/usr/include/et -Wall -Wmissing-prototypes -Wpointer-arith -Winline
-Wdeclaration-after-statement -Wendif-labels -fno-strict-aliasing
-pthread -D_GNU_SOURCE -I/usr/include -L/usr/lib conftest.c -lpam
-lssl -lcrypto -lkrb5 -lz -lreadline -ltermcap -lcrypt -ldl -lm >&5
`-mcpu=' is deprecated. Use `-mtune=' or '-march=' instead.
conftest.c: In function 'main':
conftest.c:139: warning: null argument where non-null required (argument 1)
conftest.c:140: warning: null argument where non-null required (argument 1)
conftest.c:140: warning: null argument where non-null required (argument 3)
conftest.c:138: warning: 'th' is used uninitialized in this function
configure:16484: $? = 0
configure:16488: test -z
|| test ! -s conftest.err
configure:16491: $? = 0
configure:16494: test -s conftest
configure:16497: $? = 0
configure:16535: result: no

Any ideas? This is a CentOS5 installation, only special I can think of
is that it runs as Xen domU, and I have the same problem on the dom0,
no non Xen available at the moment.

--
regards,
Robin