appveyor: Compile static openssl from git to use with opusfile.
appveyor: Compile static openssl from git to use with opusfile.

Stable branch used because master is on 1.1.x which doesn't work.

Signed-off-by: Ralph Giles <65585f72bf62a11d2f4105aa30c20fe94efea46f@thaumas.net>

SmartWalkieOrg/opusfile,xiph/opusfile,xiph/opusfile,SmartWalkieOrg/opusfile,SmartWalkieOrg/opusfile,xiph/opusfile