Remove SSL_CTX_get_extra_chain_certs_only.

This is in preparation for folding away certificate slots. extra_certs
and the slot-specific certificate chain will be the same.
SSL_CTX_get_extra_chain_certs already falls back to the slot-specific
chain if missing. SSL_CTX_get_extra_chain_certs_only is similar but
never falls back. This isn't very useful and is confusing with them
merged, so remove it.

BUG=486295

Change-Id: Ic708105bcf453dfe4e1969353d7eb7547ed2981b
Reviewed-on: https://boringssl-review.googlesource.com/5350
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index e62bffe..7b9d051 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -1860,8 +1860,6 @@
   SSL_CTX_ctrl(ctx, SSL_CTRL_EXTRA_CHAIN_CERT, 0, (char *)x509)
 #define SSL_CTX_get_extra_chain_certs(ctx, px509) \
   SSL_CTX_ctrl(ctx, SSL_CTRL_GET_EXTRA_CHAIN_CERTS, 0, px509)
-#define SSL_CTX_get_extra_chain_certs_only(ctx, px509) \
-  SSL_CTX_ctrl(ctx, SSL_CTRL_GET_EXTRA_CHAIN_CERTS, 1, px509)
 #define SSL_CTX_clear_extra_chain_certs(ctx) \
   SSL_CTX_ctrl(ctx, SSL_CTRL_CLEAR_EXTRA_CHAIN_CERTS, 0, NULL)
 
diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c
index edf0f81..0f685e7 100644
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.c
@@ -503,7 +503,7 @@
       break;
 
     case SSL_CTRL_GET_EXTRA_CHAIN_CERTS:
-      if (ctx->extra_certs == NULL && larg == 0) {
+      if (ctx->extra_certs == NULL) {
         *(STACK_OF(X509) **)parg = ctx->cert->key->chain;
       } else {
         *(STACK_OF(X509) **)parg = ctx->extra_certs;