Remove EVP_CIPHER_CTX_flags, it's only confusing

EVP_CIPHER_CTX_flags was returning the flags of its associated
EVP_CIPHER.  However, EVP_CIPHER_CTX has flags of its own, so this
function is quite confusing and therefore error prone.
Reviewed-by: NRich Salz <rsalz@openssl.org>

crypto/evp/evp_enc.c

@@ -212,7 +212,7 @@ int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
         return 0;
     }
 
-    if (!(EVP_CIPHER_CTX_flags(ctx) & EVP_CIPH_CUSTOM_IV)) {
+    if (!(EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ctx)) & EVP_CIPH_CUSTOM_IV)) {
         switch (EVP_CIPHER_CTX_mode(ctx)) {
 
         case EVP_CIPH_STREAM_CIPHER:

crypto/evp/evp_lib.c

@@ -242,11 +242,6 @@ unsigned long EVP_CIPHER_flags(const EVP_CIPHER *cipher)
     return cipher->flags;
 }
 
-unsigned long EVP_CIPHER_CTX_flags(const EVP_CIPHER_CTX *ctx)
-{
-    return ctx->cipher->flags;
-}
-
 void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx)
 {
     return ctx->app_data;

include/openssl/evp.h

@@ -526,8 +526,7 @@ void EVP_CIPHER_CTX_set_app_data(EVP_CIPHER_CTX *ctx, void *data);
 void *EVP_CIPHER_CTX_cipher_data(const EVP_CIPHER_CTX *ctx);
 void EVP_CIPHER_CTX_new_cipher_data(EVP_CIPHER_CTX *ctx, size_t size);
 # define EVP_CIPHER_CTX_type(c)         EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c))
-unsigned long EVP_CIPHER_CTX_flags(const EVP_CIPHER_CTX *ctx);
-# define EVP_CIPHER_CTX_mode(e)          (EVP_CIPHER_CTX_flags(e) & EVP_CIPH_MODE)
+# define EVP_CIPHER_CTX_mode(c)         EVP_CIPHER_mode(EVP_CIPHER_CTX_cipher(c))
 
 # define EVP_ENCODE_LENGTH(l)    (((l+2)/3*4)+(l/48+1)*2+80)
 # define EVP_DECODE_LENGTH(l)    ((l+3)/4*3+80)