fix some cppcheck warnings

fix some cppcheck warnings

use cppcheck tools `cppcheck --enable=warning  .` on lxc source directory.

This patch fix the following warnning

```
[src/lxc/cgroups/cgfs.c:794]: (warning) %ld in format string (no. 3) requires 'long' but the argument type is 'unsigned long'.
[src/lxc/confile.c:4441]: (warning) %d in format string (no. 2) requires 'int' but the argument type is 'unsigned int'.
[src/lxc/confile.c:4502]: (warning) %d in format string (no. 2) requires 'int' but the argument type is 'unsigned int'.
[src/lxc/confile_legacy.c:921]: (warning) %d in format string (no. 2) requires 'int' but the argument type is 'unsigned int'.
[src/lxc/confile_legacy.c:938]: (warning) %d in format string (no. 2) requires 'int' but the argument type is 'unsigned int'.
[src/lxc/lxclock.c:63]: (warning) %zd in format string (no. 1) requires 'ssize_t' but the argument type is 'size_t {aka unsigned long}'.
[src/lxc/tools/lxc_info.c:118]: (warning) %u in format string (no. 1) requires 'unsigned int' but the argument type is 'signed int'.
[src/lxc/tools/lxc_info.c:118]: (warning) %u in format string (no. 2) requires 'unsigned int' but the argument type is 'signed int'.
[src/lxc/tools/lxc_info.c:123]: (warning) %u in format string (no. 1) requires 'unsigned int' but the argument type is 'signed int'.
[src/lxc/tools/lxc_info.c:127]: (warning) %u in format string (no. 1) requires 'unsigned int' but the argument type is 'signed int'.
[src/lxc/tools/lxc_info.c:130]: (warning) %u in format string (no. 1) requires 'unsigned int' but the argument type is 'signed int'.
[src/lxc/tools/lxc_top.c:212]: (warning) %u in format string (no. 1) requires 'unsigned int' but the argument type is 'signed int'.
[src/lxc/tools/lxc_top.c:212]: (warning) %u in format string (no. 2) requires 'unsigned int' but the argument type is 'signed int'.
[src/lxc/tools/lxc_top.c:217]: (warning) %u in format string (no. 1) requires 'unsigned int' but the argument type is 'signed int'.
[src/lxc/tools/lxc_top.c:221]: (warning) %u in format string (no. 1) requires 'unsigned int' but the argument type is 'signed int'.
[src/lxc/tools/lxc_top.c:224]: (warning) %u in format string (no. 1) requires 'unsigned int' but the argument type is 'signed int'.
```

Signed-off-by: Long Wang <w@laoqinren.net>