Update to the latest LTS version so it's available in case something
has to be rebuilt against openssl (this version doesn't bring anything):
Major changes between OpenSSL 1.0.2k and OpenSSL 1.0.2l [25 May 2017]
- config now recognises 64-bit mingw and chooses mingw64 instead of mingw
Signed-off-by: Pierre-Yves <pyu@riseup.net>