systemui: Kill logspam

Change-Id: Id1c7c9c56632714aa6a161189d3d8e67a8a030ba
PackageInstallerSession: use ftruncate if fallocate is ENOTSUP

When posix_fallocate is not supported (e.g. on ext3), fall
back to using ftruncate instead.

Change-Id: I8f7792ed3f43504df21e86cff79ed34f3ba795d7