Includes stdio.h in log.h
Fixes perror() calls
Logs PEEKDATA failures
Logging prints tid and time
Merge branch 'master' into 'x86_64-32bit-syscalls'

Conflicts:
	reprozip/native/database.c
	reprozip/native/log.h
	reprozip/native/ptrace_utils.c
	reprozip/native/tracer.c
	reprozip/native/utils.c
	reprozip/setup.py