Fix problems reported by cppcheck

[okkez]

I fixed problems reported by cppcheck.

$ cppcheck --enable=all --force src 2> cppcheck.log

cppcheck.log:

(snip)
[src/partclone.c:760]: (error) Memory leak: real_file
(snip)
[src/progress.c:151]: (error) Buffer is accessed out of bounds.
[src/progress.c:158]: (error) Buffer is accessed out of bounds.
[src/progress.c:171]: (error) Buffer is accessed out of bounds.
(snip)