package/openssl: bin/openssl depends on dynamic linking

Fixes
/home/br/br3/output/host/usr/lib/gcc/i586-buildroot-linux-uclibc/4.8.4/../../../../i586-buildroot-linux-uclibc/bin/ld: cannot find -ldl

using this defconfig

BR2_STATIC_LIBS=y
BR2_PACKAGE_OPENSSL=y
BR2_PACKAGE_OPENSSL_BIN=y

Quoting PROBLEMS:
"We don't have framework to associate -ldl with no-dso, therefore the only
way is to edit Makefile right after ./config no-dso and remove -ldl from
EX_LIBS line."

To not make the build procedure more complicated disable static building of
bin/openssl.

[Thomas: add corresponding kconfig comment.]

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