Convert the project to use the GNU Build System (aka Autotools)

LICENSE was renamed COPYING because otherwise `autoreconf` complains loudly.
This is also the reason AUTHORS, INSTALL, and README were created.

Man pages were moved into src/pam_panic/man and src/pam_panic_pw/man.

Finally, certain variables are passed through the config.h file to the
module rather than as -D flags on the command-line.

m4/.gitignore

@@ -0,0 +1,5 @@
+libtool.m4
+ltoptions.m4
+ltsugar.m4
+ltversion.m4
+lt~obsolete.m4