package/libcurl: make sure openssl supports DES

package/libcurl: make sure openssl supports DES

DES support in openssl is optional since commit a83d41867c8d
("package/libopenssl: add option to enable some features"). curl uses
DES support in openssl when enabled. Select DES support to avoid build
failure.

Fixes:
http://autobuild.buildroot.net/results/8931fd2b71eb2490cdc041b47eff58377ac823da/
http://autobuild.buildroot.net/results/f159195adf05c375d7d314a270afd3a55d43ebdd/
http://autobuild.buildroot.net/results/e143c75bccd7bcd4216954b76099404a38cf9bc1/

Cc: Erwan GAUTRON <erwan.gautron@bertin.fr>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Reviewed-by: Matthew Weber <matthew.weber@collins.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>