init-db: remove unnecessary global variable

init-db: remove unnecessary global variable

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.  One issue that made it difficult was the
init_is_bare_repository global variable.

init_is_bare_repository's sole use in life it to cache a value in
init_db(), and then be used in create_default_files().  This is a bit
odd since init_db() directly calls create_default_files(), and is the
only caller of that function.  Convert the global to a simple function
parameter instead.

(Of course, this doesn't fix the fact that this value is then ignored by
create_default_files(), as noted in a big TODO comment in that function,
but it at least includes no behavioral change other than getting rid of
a very questionable global variable.)

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