Fix an uninit read picked up by Travis
Fix an uninit read picked up by Travis

The siglen value needs to be initialised prior to it being read in the
call to EVP_DigestSignFinal later in this function.

Reviewed-by: Rich Salz <c04971a99e5a9ee80eaab4b1deb37e845b0bd697@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2157)
openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl