Use 'gcc -M' instead of 'makedepend'

- Use 'gcc -M' instead of 'makedepend' so that there is n more need to
install xutils-dev in order to compile this project
Suppress compilation warnings on 32 bits OS

- When compiling on a 32 bits OS, there were warnings related to printf
of sizeof. These warnings were due to the fact that sizeof returns a
long unsigned in 64 bits and a plain unsigned in 32 bits. Thus
we used %lu not to have any warnings when compiling on a 64 bits OS.
But %lu generates a warning on 32 bits OS.
To correct this problem, we replace %lu by %zu, as %zu is a format designed
to avoid compilation warnings related to sizeof different size on 32 bits
and 64 bits OS.
Suppress compilation warning related to unitialized variable