Looking at the list of symbols inside of libruby-static.a, I found
hundreds of functions that are defined, but used from nowhere.

There can be reasons for each of them (e.g. some functions are
specific to some platform, some are useful when debugging, etc).
However it seems the functions deleted here exist for no reason.

This changeset reduces the size of ruby binary from 26,671,456
bytes to 26,592,864 bytes on my machine.