[ccache] More win32 patches

[Ramiro Polla]

Hi,

I've updated my github fork at:
http://github.com/ramiropolla/ccache

- There is no strtok_r() on Windows, I've implemented an ugly
replacement using strtok().
- The ar check on configure.ac fails for cross-compilation. I haven't
investigated why, I've just removed it, but I suppose it's there for a
reason so it's better to fix than to remove =)
- Make test on Windows requires a certain dd to work (one that can
emulate /dev/zero). It's the one found here:
http://www.chrysocome.net/dd
- %APPDATA% is chosen as home on Windows if $HOME is not found. This
makes ccache work on cmd.exe. Could someone please test whether it now
works on CodeBlocks?
- Executables with dots in the filename are now properly found.
- Checks for win32 directories before stat (I faintly remember already
having done something similar before, but out-of-tree builds were no
longer being cache directly).

Joel, is there a way we can time how long each part of ccache takes?
Not just a whole batch of tests, but it would be nice if under a
certain ifdef we could print to the ccache log the time it takes to
perform each step. It seems to have gotten slower on Windows since the
first port I've made (either that or FFmpeg has grown a lot too).

Ramiro Polla