rename channels to channels_builtin (#17330)

* improve test coverage for isolation

* a bit better

* rename channels to channels_builtin

doc/lib.rst

@@ -39,7 +39,7 @@ Automatic imports
   Basic Nim thread support. **Note:** This is part of the system module. Do not
   import it explicitly. Enabled with ``--threads:on``.
 
-* `channels <channels.html>`_
+* `channels <channels_builtin.html>`_
   Nim message passing support for threads. **Note:** This is part of the
   system module. Do not import it explicitly. Enabled with ``--threads:on``.
 

doc/manual.rst

@@ -7721,7 +7721,7 @@ Threads
 
 To enable thread support the ``--threads:on`` command-line switch needs to
 be used. The ``system`` module then contains several threading primitives.
-See the `threads <threads.html>`_ and `channels <channels.html>`_ modules
+See the `threads <threads.html>`_ and `channels <channels_builtin.html>`_ modules
 for the low-level thread API. There are also high-level parallelism constructs
 available. See `spawn <manual_experimental.html#parallel-amp-spawn>`_ for
 further details.

lib/pure/collections/deques.nim

@@ -46,7 +46,7 @@ runnableExamples:
 ## See also
 ## ========
 ## * `lists module <lists.html>`_ for singly and doubly linked lists and rings
-## * `channels module <channels.html>`_ for inter-thread communication
+## * `channels module <channels_builtin.html>`_ for inter-thread communication
 
 import std/private/since
 

lib/pure/concurrency/threadpool.nim

@@ -14,7 +14,7 @@
 ## See also
 ## ========
 ## * `threads module <threads.html>`_ for basic thread support
-## * `channels module <channels.html>`_ for message passing support
+## * `channels module <channels_builtin.html>`_ for message passing support
 ## * `locks module <locks.html>`_ for locks and condition variables
 ## * `asyncdispatch module <asyncdispatch.html>`_ for asynchronous IO
 

lib/system.nim

@@ -2385,7 +2385,7 @@ when notJSnotNims and hasAlloc:
     include "system/repr"
 
 when notJSnotNims and hasThreadSupport and hostOS != "standalone":
-  include "system/channels"
+  include "system/channels_builtin"
 
 
 when notJSnotNims and hostOS != "standalone":

tools/kochdocs.nim

@@ -126,7 +126,7 @@ gc.rst
 
   doc0 = """
 lib/system/threads.nim
-lib/system/channels.nim
+lib/system/channels_builtin.nim
 """.splitWhitespace() # ran by `nim doc0` instead of `nim doc`
 
   withoutIndex = """