Fix a bogus clang warning

Fix a bogus clang warning

Clang with --strict-warnings was complaining about an uninitalised
variable. In reality it will never be used uninitialised but clang can't
figure out the logic, so just init it anyway to silence the warning.

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