Add C API function PyCompile_OpcodeStackEffectWithJump().

generated by Argument Clinic.  Patch by Petr Viktorin.

The new syntax is highly human readable while still preventing false
positives.  The syntax also extends Python syntax to denote "self" and
positional-only parameters, allowing inspect.Signature objects to be
totally accurate for all supported builtins in Python 3.4.

including correctly generating code for Clinic blocks inside C
preprocessor conditional blocks.

annotate text signatures in docstrings, resulting in fewer false
positives.  "self" parameters are also explicitly marked, allowing
inspect.Signature() to authoritatively detect (and skip) said parameters.

Issue #20326: Argument Clinic now generates separate checksums for the
input and output sections of the block, allowing external tools to verify
that the input has not changed (and thus the output is not out-of-date).

PyMethodDescr_Type, _PyMethodWrapper_Type, and PyWrapperDescr_Type)
have been modified to provide introspection information for builtins.
Also: many additional Lib, test suite, and Argument Clinic fixes.

docstring for __new__ and __init__, and always use "goto exit" instead of
returning "NULL" for failure to parse (as _new__ and __init__ return ints).