Avoid calling idmap w/ trailing whitespace [2/2]

installd performs a buffer over-read if trailing ws is sent to it.
No observable effect found yet for idmap, but until installd is
fixed upstream, best to play it safe.

Change-Id: I002de7a9d177df16f91b47e7f87af59457c1f421
(cherry picked from commit a852d21d84635053fffbcb9322206f7b3c89515c)