Fix typos in comments, docs and test names (#15018)

* Fix typos in comments, docs and test names

* Update test_pyparse.py

account for change in string length

* Apply suggestion: splitable -> splittable

Co-Authored-By: Terry Jan Reedy <tjreedy@udel.edu>

* Apply suggestion: splitable -> splittable

Co-Authored-By: Terry Jan Reedy <tjreedy@udel.edu>

* Apply suggestion: Dealloccte -> Deallocate

Co-Authored-By: Terry Jan Reedy <tjreedy@udel.edu>

* Update posixmodule checksum.

* Reverse idlelib changes.
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 103a111..a89ebce 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1162,7 +1162,7 @@
 PyDoc_STRVAR(asyncgen_hooks_doc,
 "asyncgen_hooks\n\
 \n\
-A struct sequence providing information about asynhronous\n\
+A struct sequence providing information about asynchronous\n\
 generators hooks.  The attributes are read only.");
 
 static PyStructSequence_Field asyncgen_hooks_fields[] = {