resolv: Remove support for RES_USE_INET6 and the inet6 option

This functionality was deprecated in glibc 2.25.

This commit only includes the core changes to remove the
functionality.  It does not remove the RES_USE_INET6 handling in the
individual NSS service modules and the res_use_inet6 function.
These changes will happen in future commits.

1 files changed, 4 insertions, 7 deletions

diff --git a/resolv/resolv_context.h b/resolv/resolv_context.h
index a4d97738a7..b1114343e6 100644
--- a/resolv/resolv_context.h
+++ b/resolv/resolv_context.h
@@ -26,9 +26,7 @@
    allocating a new context.  This prevents unexpected reloading of
    the resolver configuration.  Care is taken to keep the context in
    sync with the thread-local _res object.  (This does not happen with
-   __resolv_context_get_override, and __resolv_context_get_no_inet6 may
-   also interpose another context object if RES_USE_INET6 needs to be
-   disabled.)
+   __resolv_context_get_override.)
 
    In contrast to struct __res_state, struct resolv_context is not
    affected by ABI compatibility concerns.
@@ -62,8 +60,8 @@ struct resolv_context
   size_t __refcount;            /* Count of reusages by the get functions.  */
   bool __from_res;              /* True if created from _res.  */
 
-  /* If RES_USE_INET6 was disabled at this level, this field points to
-     the previous context.  */
+  /* Single-linked list of resolver contexts.  Used for memory
+     deallocation on thread cancellation.  */
   struct resolv_context *__next;
 };
 
@@ -75,8 +73,7 @@ struct resolv_context *__resolv_context_get (void)
 libc_hidden_proto (__resolv_context_get)
 
 /* Deallocate the temporary resolver context.  Converse of
-   __resolv_context_get.  Restore the RES_USE_INET6 flag if necessary.
-   Do nothing if CTX is NULL.  */
+   __resolv_context_get.  Do nothing if CTX is NULL.  */
 void __resolv_context_put (struct resolv_context *ctx);
 libc_hidden_proto (__resolv_context_put)