init-db, clone: change unnecessary global into passed parameter

init-db, clone: change unnecessary global into passed parameter

Much like the parent commit, this commit was prompted by a desire to
move the functions which builtin/init-db.c and builtin/clone.c share out
of the former file and into setup.c.  A secondary issue that made it
difficult was the init_shared_repository global variable; replace it
with a simple parameter that is passed to the relevant functions.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>