Avoid strict-prototype compiler errors

Avoid strict-prototype compiler errors

Commit 4b9d7f7c107f01a61600fddcd8cde3812d0366a2 added the
-Werror=strict-prototypes parameter to the build process, but left
behind 28 function definitions using "()" instead of "(void)".  Most
of these definitions could not cause compiler errors for various
reasons (such as an accompanying prototype), but a few could cause
errors in gcc depending on the build configuration.

For consistency and safety, add "(void)" to all 28 definitions.

[ghudson@mit.edu: rewrote commit message]