Use functions with prototypes when appropriate; NFC

Use functions with prototypes when appropriate; NFC

A significant number of our tests in C accidentally use functions
without prototypes. This patch converts the function signatures to have
a prototype for the situations where the test is not specific to K&R C
declarations. e.g.,

  void func();

becomes

  void func(void);

This is the fourth batch of tests being updated (there are a significant
number of other tests left to be updated).