configuring library path for debian build of postgres 9.2

I'm trying to build postgres 9.2 beta1 on debian stable from sources, in
a way that plays nicely with the debian cluster management stuff.

If I configure with libdir=/usr/lib/postgres everything works but the
shared libraries end up in the wrong place (ie just where I specified).

If I configure with libdir=/usr/lib/postgresql/9.2, which is where I
want the libraries to go, psql complains:

$ /usr/lib/postgresql/9.2/bin/psql: symbol lookup
error: /usr/lib/postgresql/9.2/bin/psql: undefined symbol:
PQconnectdbParams

Here is my configure command:

$ ./configure --build=i486-linux-gnu --prefix=/usr
--includedir=/usr/include/postgresql/9.2
--mandir=/usr/share/postgresql/9.2/man
--infodir=/usr/share/postgresql/9.2/info
--sysconfdir=/etc/postgresql-common --localstatedir=/var
--libexecdir=/usr/lib/postgresql/9.2 --libdir=/usr/lib/postgresql/9.2
--srcdir=. -docdir=/usr/share/doc/postgresql-doc-9.2
--datadir=/usr/share/postgresql/9.2/
--bindir=/usr/lib/postgresql/9.2/bin --enable-nls
--enable-integer-datetimes --enable-thread-safety --enable-debug
--disable-rpath --with-perl --with-python --with-pam --with-krb5
--with-gssapi --with-openssl --with-libxml --with-libxslt --with-ldap
--with-ossp-uuid --with-gnu-ld --with-system-tzdata=/usr/share/zoneinfo
CFLAGS='-g -O2 -g -Wall -O2 -fPIC' LDFLAGS=' -Wl,--as-needed'

I'd appreciate any suggestions.

In the short term I can live with the libraries being in the wrong place
for one postgres version but it isn't viable in the longer term.
Ultimately I'd like to be able to build a debian-compatible postgres
cluster directly from the repository.

Thanks.

__
Marc