The log says:
:info:build Undefined symbols for architecture x86_64:
:info:build "___sincos_stret", referenced from:
:info:build _main in tclock.o
:info:build ld: symbol(s) not found for architecture x86_64
This is new to me. It builds fine for me on Mavericks.
Is it possible you have an old version of Xcode or its command line tools? A developer preview perhaps? Googling this error led me to this stack overflow post which says uninstalling and reinstalling Xcode and the command line tools fixes this problem.