Change function definitions using the identifier-list form used in the

Change function definitions using the identifier-list form used in the
1st edition of Kernighan and Ritchie's The C Programming Language, to
that of the parameter-type-list form described in the ANSI X3.159-1989
standard.

In ISO/IEC 9899:2023 drafts, there is only one form of function definition.
"N2432 Remove support for function definitions with identifier lists".