Avoid more implicit function declarations

[fweimer-rh]

Implicit funciton declarations were removed from C99, and future compilers may not support them by default because they are a type safety hazard.

This commit fixes ucblogo for the Fedora build configure, so it will continue to build with such future compilers.

Related to:

• https://fedoraproject.org/wiki/Changes/PortingToModernC
• https://fedoraproject.org/wiki/Toolchain/PortingToModernC