src/udev/udev-ctrl.c: explicitly declare return value

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
src/udev/mkdir.c: import path_startswith() from upstream

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
src/udev/udev-builtin-kmod.c: fix const char* declaration

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>