Fix to build better with DJGPP.

PR: 338

Here's the description, submitted by Gisle Vanem <giva@bgnett.no>:

1. sock_init() renamed to ssl_sock_init() in ./apps/s_socket.c due
   to name-clash with Watt-32.

2. rand() renamed to Rand() in ./crypto/bn/divtest.c due to name-clash
   with <stdlib.h>

3. Added calls to dbug_init()/sock_init() in some demo programs.

4. Changed cflags/lflags in configure. Watt-32 install root now taken
   from $WATT_ROOT.