Config.h and using gcc's -fno-builtin. There are probably other files
with the similar problems.
Also, if building against uClibc, don't include asm/unistd.h in syscalls.c
and module_syscalls.c.
1) fixed a bug that could crash df, mount, and umount applets if the root
device name was longer then the word "root" (/dev/loop1 vs /dev/root) -
2) severl functions needed static declaration in the umount applet
3) update declaration for function in last_char_is() in libbb
