lint: remove or comment out unused functions

Cppcheck has identified a lot of unused functions. This removes funcs that
are unlikely to ever be used. Others that might be useful for debugging I've
commented out with "#if 0".

1 files changed, 3 insertions, 1 deletions

diff --git a/src/io.h b/src/io.h
index adc59be1..181099ad 100644
--- a/src/io.h
+++ b/src/io.h
@@ -304,7 +304,9 @@ struct io_streams_t
     }
 };
 
-/** Print debug information about the specified IO redirection chain to stderr. */
+#if 0
+// Print debug information about the specified IO redirection chain to stderr.
 void io_print(const io_chain_t &chain);
+#endif
 
 #endif