sysvinit: added libselinux dependency

sysvinit: added libselinux dependency

[Thomas:
  - remove the patch from Matthew Weber that did a lot of changes that
    were not needed: the CFLAGS would not get overridden by Buildroot
    ones if the Buildroot TARGET_CONFIGURE_OPTS is passed on the left
    hand-side of make, and the SULOGINLIBS hack needs to be replaced
    by a proper handling of the libcrypt detection.
  - added a patch that changes the libcrypt detection logic to accept
    a SYSROOT variable. Instead of search for /usr/lib/libcrypt.a, it
    search for $(SYSROOT)/usr/lib/libcrypt.a. This avoids the need for
    overriding SULOGINLIBS.
  - don't modify TARGET_CONFIGURE_OPTS in sysvinit.mk, this is
    completely forbidden and broken.
  - don't pass ROOT= since we don't use 'make install' anyway.]

Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
Reviewed-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>