LU-11960 build: Add missing libssl-dev DEB package

LU-11960 build: Add missing libssl-dev DEB package

Building Lustre client DEB packages on Debian fails due to missing
package libssl-dev and results in error:
"No such file or directory #include <openssl/evp.h>"
Add required package libssl-dev into "make debs" chain.

Test-Parameters: clientdistro=ubuntu1804 envdefinitions=SANITY_EXCEPT=802a trivial
Signed-off-by: Thomas Stibor <t.stibor@gsi.de>
Change-Id: Ib99cd744b2d44d3f6c1915e2f2d2da7d83e07cae
Reviewed-on: https://review.whamcloud.com/34233
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>