Function nginx::EVP_PKEY_meth_set_signctx

pub unsafe extern "C" fn EVP_PKEY_meth_set_signctx(
    pmeth: *mut EVP_PKEY_METHOD, 
    signctx_init: Option<unsafe extern "C" fn(ctx: *mut EVP_PKEY_CTX, mctx: *mut EVP_MD_CTX) -> c_int>, 
    signctx: Option<unsafe extern "C" fn(ctx: *mut EVP_PKEY_CTX, sig: *mut c_uchar, siglen: *mut size_t, mctx: *mut EVP_MD_CTX) -> c_int>
)