Add zsh completion for targets in conjunction with -C

zsh can now list completions for targets in the directory specified by
the -C option
Merge pull request #834 from frasercrmck/master

Add zsh completion for targets in conjunction with -C
Update line_printer.cc

Include POSIX termios.h
Merge pull request #837 from ppbrown/master

Update line_printer.cc with termios.h
CanonicalizePath handles \ on Windows
Merge pull request #840 from sgraham/canon-win-squashed

CanonicalizePath handles \ on Windows
Use strchr in \ conversion in CanonicalizePath on Windows
Merge pull request #841 from sgraham/strchr

Use strchr in \ conversion in CanonicalizePath on Windows