mke2fs: fix project quota creation

mke2fs: fix project quota creation

Creating a file system with project quotas can fail if mke2fs is built
using hardening options.  This is because quota_compute_usage() used
ext2fs_get_next_inode() instead of ext2fs_get_inode_full(), and a
small inode was passed into quota_data_add, when a large inode needs
to be used.  As a result get_dq() would end up dereferencing undefined
space in the stack.  Without the hardening options, this would be
zero, so "mke2fs -t ext4 -O project.quota -I 256 test.img" would work
essentially by accident.

Fix this by using ext2fs_get_inode_full() so that a large inode is
available to quota_data_inodes().

Signed-off-by: Theodore Ts'o <tytso@mit.edu>