sudo: fix static linking with openldap having openssl support

sudo: fix static linking with openldap having openssl support

If we are building sudo statically and openldap was linked with openssl,
then when we link sudo with openldap we need to specify the openssl
libs, otherwise it will fail with "undefined reference" errors.

Fixes:
  http://autobuild.buildroot.net/results/ebb/ebbb4c3138b5023a0c8bd938db1932a25ba5b6fb/
  http://autobuild.buildroot.net/results/58e/58ee4fddea85f0c79b26582b04a573258e27eb47/
  http://autobuild.buildroot.net/results/051/05151c4ef7f0b3702a6cd5e6df4888d826a37431/
  http://autobuild.buildroot.net/results/b1d/b1dfae81985daee106700191fcb82387833c2e3f/
  http://autobuild.buildroot.net/results/5b4/5b42e8505856156389d480d0da19f6982cf120d8/
  http://autobuild.buildroot.net/results/30a/30a76190428f902f03bcf54ba9f1f4f4377c6fc9/
  http://autobuild.buildroot.net/results/e8c/e8c6bdc314b9a8d5de303633a3abd7b7e44beb2e/
  http://autobuild.buildroot.net/results/483/4830c69cc6a62080e1516f0d9009c2ba619c23c1/

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>