ecc: Fix memory leak in the error case of ecc_encrypt_raw
* cipher/ecc.c (ecc_encrypt_raw): Add proper error cleanup in the main block.
(cherry picked from commit e57e75ea517f32109b508113f18298fc69fd1192)
- GnuPG-bug-id: T4210
- Signed-off-by: Werner Koch <wk@gnupg.org>