These bad calls to putenv suddenly caused the buildIdFile string (macro-expanded
from bootstraprc's UserInstallation) in cleanExtensionCache
(desktop/source/app/app.cxx) to contain nonsense at least in a local
libreoffice-4-0-0 of mine, as getenv("UserInstallation") started to return some
non-null pointer pointing to garbage.

Change-Id: Ib93fd4e1caef016bd0e00bf09800b9532824ac4b
(cherry picked from commit d841273b)
Reviewed-on: https://gerrit.libreoffice.org/1917Reviewed-by: Tor Lillqvist <tml@iki.fi>
Tested-by: Tor Lillqvist <tml@iki.fi>