e2fsdroid: Fix incorrect error value handling.

Methods returning 0 or -1 should not pass their return value to com_err.
Also, errno values should not be negated when passed to com_err or
through errcode_t.

Bug: N/A
Test: manual test

Change-Id: I5e25cf2deeee72668bf0ab58337ee582bf14bbc1
1 file changed