add missing "memdbg_defines.h" file
Fix problems with gpg2john that came (back?) after memdbg merge.
Rexgen "autoconf" fix for Linux.
Use Atom's fgets_sse2 for fgetl(), affecting unbuffered wordlist
mode, pot reload and unique (among other things).

This shaves 3 seconds off running unique on rockyou dataset, from
17 seconds to 14.