mkuserimg_mke2fs: fix issues creating images

Don't add slash before mount point unless there's none. Extra
slash confuses fs_config when looking up for selinux entries.

Truncate output file before running mke2fs since it keeps verity
section appened in the end of ext4 image. Otherwise build system
will append verity twice.

Change-Id: I076050b82c15e923aa87f3a98c258aa39b64b112
1 file changed