git-p4: remove tabs from usermap file

git-p4: remove tabs from usermap file

Some users have tabs in their names, oddly enough.  This
causes problems when loading the usercache from disk,
as split separates the fields on the wrong tabs.  When
fast-import's parse_ident() tries to parse the committer
field, it is unhappy about the unbalanced <..> angle brackets.

It is easy enough to convert the tabs to single spaces.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Acked-by: Simon Hausmann <simon@lst.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>