Autoconf, initial work.
Add autoconf stuff to .gitignore
Fix for Travis/Coverity scan now that we use ./configure
JtR-autoconf-2.patch
JtR-autoconf-3.patch
Add autoconfig stuff to .gitignore, and add some macros we will
need later (ax_opencl.m4 and ax_prog_cc_mpi.m4).
JtR-autoconf-v3.patch
Allow for NSS to be missing.
Rename configure.in to configure.ac - the former has been deprecated
since 2001.
Change final message from configure to something less confusing.
Rename HAVE_LIBCRYPT to HAVE_CRYPT for several reasons, mainly because
it's what core John uses. One other reason is that we no longer really
depend on the library per se, but the function (it might be present in
libc).

Also revert a change that broke build on OSX and likely others.
JtR-autoconf-v3a.patch
Whitespace fixes (a dnl comment was split by a linefeed)
Change final message from configure (again) to something less confusing.
Autoconf fix for pcap.
Add CUDA and/or OpenCL stuff to JOHN_OBJS if applicable.
Decrease required version of autoconf to 2.68, for Travis CI to work.
Autoconf: Use proper OpenCL test macro instead of just checking for lib.
Also adds [suddenly] required autohell stuff.
Add real copies of compile, config.guess and config.sub (they were
symlinks).
OpenCL autoconf tweak.