* Compiling a string annotation containing a lambda with keyword-only
argument without default value caused a crash.

* Remove the final "*" (it is incorrect syntax) in the representation of
lambda without *args and keyword-only arguments when compile from AST.

* Improve the representation of lambda without arguments.
(cherry picked from commit 2a2940e5)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>