package/openssl: drop libdl from more pc files

This is a follow-up patch for
http://git.buildroot.net/buildroot/commit/package/openssl/openssl.mk?id=c130c5d4635e2a4c7338161953152faf8fca07c4

Fixes
http://autobuild.buildroot.net/results/358/35899961b6dc01c1522b17f63946da5ab809bff8/
http://autobuild.buildroot.net/results/c86/c865214e74dd3766b6343ef73c666fa89c0b5dec/
http://autobuild.buildroot.net/results/fc1/fc12e88fb789e2b68d427c37f39789954309b05d/
http://autobuild.buildroot.net/results/f4d/f4deef4e7d2e2cf5fbc9ce5f02289b4dc60cd23b/
http://autobuild.buildroot.net/results/dfd/dfd81f1f1f0f315317b2a85d24b286a277ac7c16/
http://autobuild.buildroot.net/results/918/9188fc9a63d880cac28c5a9a246ca5504dd11bb2/
http://autobuild.buildroot.net/results/dd1/dd1c326345f8f9c8b5838601ace19002f5360bb2/
http://autobuild.buildroot.net/results/27b/27b4544c59166a9f40092403ed3f530190544a82/
http://autobuild.buildroot.net/results/c37/c37022e334d763bad2a59f7311b93504a569b2dd/
http://autobuild.buildroot.net/results/e89/e89265937a6b4808b817be16bcab79bae4a9aed1/
http://autobuild.buildroot.net/results/4a2/4a222a40d627fda6e49714b13b4321d62c9c2e51/



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>