wolfssl: new package

The wolfSSL embedded SSL library is a lightweight and portable
SSL/TLS library.

Tested on Beaglebone Black using a tool called testsuite that
comes with wolfssl source code inside the testsuite/ directory.
To build it, we have to pass --enable-examples in the configure,
and then manually copy the binary to the rootfs. Also, to use
this tool, you will we need to copy the certs/* directory to the
rootfs.

Build-tested with test-pkg script.

Signed-off-by: Sergio Prado <sergio.prado@e-labworks.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>