repl.c, replsbr.c: Move shared data into header file.

repl.c, replsbr.c: Move shared data into header file.

repl.c declared global variables, and replsbr.c had extern statements
that hopefully matched them.  But they're really inputs into replsbr.c's
code, so move the declarations into a new header file that both then
include, and define them in replsbr.c.