Clean up fprintf usage

```
Fjalar and Kvasir use a mixture of printf, fprintf, puts, fputs, and others.  
Some of these are handled by my_libc.c and some are handled by Valgrind (via 
the VG_ prefix).  This leads to different output (due to different 
implementations of format chars) and some mixed up buffering.


```

Original issue reported on code.google.com by `mar...@cs.washington.edu` on 5 Aug 2013 at 9:40
