Fix memory leak in the apps

The BIO_free() allocated ex_data again that we already freed.

Reviewed-by: Richard Levitte <levitte@openssl.org>
dlfcn: always define _GNU_SOURCE

We need this for the freebsd kernel with glibc as used in the Debian kfreebsd
ports.  There shouldn't be a problem defining this on systems not using glibc.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Document openssl dgst -hmac option

Signed-off-by: Kurt Roeckx <kurt@roeckx.be>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Make "run" volatile

RT#3629

Reviewed-by: Richard Levitte <levitte@openssl.org>