[libc] Fix WrapperGen seeing no arguments as a void argument.

This corrects WrapperGen generating incorrect wrappers for functions
that take no arguments. Previously it would generate a wrapper with a
single argument of type `void`.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D90800

GitOrigin-RevId: 5c801de13cc2b615e2248be9845190bd1f5ef60f
1 file changed