Thanks guys, it works!
The lib/dbd directory was indeed empty, and I recompiled the
libdbi-drivers with the correct switches:
./configure --disable-docs --without-oracle \
--with-dbi --with-dbi-incdir='${prefix}/include/'
--with-dbi-libdir='${prefix}/lib/' \
--with-freetds --with-mysql --with-pgsql \
--with-sqlite3 --without-sqlite \