openssl: add ecc_pkey_new(), ecc_pkey_from_curve_x_y(), ecc_pkey_to_curve_x_y()

openssl: add ecc_pkey_new(), ecc_pkey_from_curve_x_y(), ecc_pkey_to_curve_x_y()

Add function to create openssl pkey from ECC curve and point, and function to
get curve id and x/y point from existing ECC pkey. Also add function to create
new ECC key for specified curve.

Also add DEFINE_TRIVIAL_CLEANUP_FUNC_FULL_MACRO() to handle case when func() is
a macro, not a function symbol; specifically in this case it is used for
OPENSSL_free() which is a macro.