Deterministic time

[rbalint]

Please test it on Apple. There were many changes but I could not test them.

[wolfcw]

Some comments w.r.t. Mac OS X:

ft_shm_init and next_time are declared within #ifdef FAKE_STAT, which is not set in the Mac OS X Makefile by default, and therefore libfaketime/deterministic-time cannot be compiled on OS X at the moment (it's certainly also broken on other OS when compiled without FAKE_STAT). I think I fixed this for the master branch after merging your last commit by moving both functions (as well as ft_cleanup and the two new global ticks-variables) in front of the offending #ifdef (line 92), and did so again for my tests. With these minor changes, the library compiles cleanly and its basic functionality still works.

Could you please fix the #ifdef FAKE_STAT issue? It also seems to prevent automatic merging.

Also, do you have a list of tests, which you perform on Linux for your new features? I can try the same on OS X then.

[rbalint]

I have fixed the FAKE_STAT issue, sorry for not rebasing my branch earlier.

I only performed manual testing trying the commands listed in --help.
I compile with PREFIX set to the development dir and tested the file loading/saving like this:
FAKETIME_SAVE_FILE=/home/.../asdfasdf ./faketime -f '+2,5y i2,0' /bin/bash -c 'date; while true; do date; sleep 1 ; done'
FAKETIME_LOAD_FILE=/home/.../asdfasdf ./faketime -f '+2,5y i2,0' /bin/bash -c 'date; while true; do date; sleep 1 ; done'

I think automatic test coverage could be extended by adding faketime [-l lib-path] parameter and running faketime from the test scripts instead of setting up environment variables as new features require faketime to set up shared memory.