cpool: rename "connection cache/conncache" to "Connection Pools/cpool"

This is a better match for what they do and the general "cpool"
var/function prefix works well.

The pool n

cpool: rename "connection cache/conncache" to "Connection Pools/cpool"

This is a better match for what they do and the general "cpool"
var/function prefix works well.

The pool now handles very long hostnames correctly.

The following changes have been made:

* 'struct connectdata', e.g. connections, keep new members
named `destination` and ' destination_len' that fully specifies
interface+port+hostname of where the connection is going to.
This is used in the pool for "bundling" of connections with
the same destination. There is no limit on the length any more.
* Locking: all locks are done inside conncache.c when calling
into the pool and released on return. This eliminates hazards
of the callers keeping track.
* 'struct connectbundle' is now internal to the pool. It is no
longer referenced by a connection.
* 'bundle->multiuse' no longer exists. HTTP/2 and 3 and TLS filters
no longer need to set it. Instead, the multi checks on leaving
MSTATE_CONNECT or MSTATE_CONNECTING if the connection is now
multiplexed and new, e.g. not conn->bits.reuse. In that case
the processing of pending handles is triggered.
* The pool's init is provided with a callback to invoke on all
connections being discarded. This allows the cleanups in
`Curl_disconnect` to run, wherever it is decided to retire
a connection.
* Several pool operations can now be fully done with one call.
Pruning dead connections, upkeep and checks on pool limits
can now directly discard connections and need no longer return
those to the caller for doing that (as we have now the callback
described above).
* Finding a connection for reuse is now done via `Curl_cpool_find()`
and the caller provides callbacks to evaluate the connection
candidates.
* The 'Curl_cpool_check_limits()' now directly uses the max values
that may be set in the transfer's multi. No need to pass them
around. Curl_multi_max_host_connections() and
Curl_multi_max_total_connections() are gone.
* Add method 'Curl_node_llist()' to get the llist a node is in.
Used in cpool to verify connection are indeed in the list (or
not in any list) as they need to.

I left the conncache.[ch] as is for now and also did not touch the
documentation. If we update that outside the feature window, we can
do this in a separate PR.

Multi-thread safety is not achieved by this PR, but since more details
on how pools operate are now "internal" it is a better starting
point to go for this in the future.

Closes #14662

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hyper: fix EOF handling on input

We ran out of disc space due to an infinite loop with debug logging

Fixes #11377
Closes #11385
Reported-by: Dan Fandrich

test1554: adjust for hyper

Closes #8104

tests: use %TESTNUMBER instead of fixed number

This makes the tests easier to copy and relocate to other test numbers
without having to update content.

Closes #6738

tests: fixup several tests

missing CRs and modified %hostip

lib556/test556: use a real HTTP version to make test reuse more convenient

make sure the weekday in Date headers

tests: fixup several tests

missing CRs and modified %hostip

lib556/test556: use a real HTTP version to make test reuse more convenient

make sure the weekday in Date headers matches the date

test61: replace stray "^M" (5e 4d) at the end of a cookie with a '^M' (0d)

Gets the test working with external proxies like Privoxy again.

Closes #6463

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multi_remove_handle: close unused connect-only connections

Previously any connect-only connections in a multi handle would be kept
alive until the multi handle was closed. Since these c

multi_remove_handle: close unused connect-only connections

Previously any connect-only connections in a multi handle would be kept
alive until the multi handle was closed. Since these connections cannot
be re-used, they can be marked for closure when the associated easy
handle is removed from the multi handle.

Closes #5749

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conncache: various concept cleanups

More connection cache accesses are protected by locks.

CONNCACHE_* is a beter prefix for the connection cache lock macros.

Curl_attach_c

conncache: various concept cleanups

More connection cache accesses are protected by locks.

CONNCACHE_* is a beter prefix for the connection cache lock macros.

Curl_attach_connnection: now called as soon as there's a connection
struct available and before the connection is added to the connection
cache.

Curl_disconnect: now assumes that the connection is already removed from
the connection cache.

Ref: #4915
Closes #5009

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conncache: fix multi-thread use of shared connection cache

It could accidentally let the connection get used by more than one
thread, leading to double-free and more.

Reported-b

conncache: fix multi-thread use of shared connection cache

It could accidentally let the connection get used by more than one
thread, leading to double-free and more.

Reported-by: Christopher Reid
Fixes #4544
Closes #4557

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conn: remove the boolean 'inuse' field

... as the usage needs to be counted.

conncache: fix several lock issues

If the lock is released before the dealings with the bundle is over, it may
have changed by another thread in the mean time.

Fixes #2132
F

conncache: fix several lock issues

If the lock is released before the dealings with the bundle is over, it may
have changed by another thread in the mean time.

Fixes #2132
Fixes #2151
Closes #2139

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test1554: verify connection cache sharing