Fix some longstanding environment bugs

[Sascha Hauer]

When an environment doesn't fit into the environment partition saveenv
still returned success. Also loading this corrupted partition resulted
in success. Fix this.

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Sascha Hauer (4):
      unlink_recursive: return negative error value
      loadenv: ignore -ENOENT when removing /env
      saveenv: Properly detect write errors
      loadenv: detect truncated environment files

 commands/loadenv.c     |  2 +-
 common/environment.c   | 38 ++++++++++++++++++++++++++++----------
 lib/unlink-recursive.c |  2 +-
 3 files changed, 30 insertions(+), 12 deletions(-)