After libsepol is modified (for example while developing new features or
fixing bugs), running "make install" in the top-level directory does not
update the programs which use libsepol.a. Add this static library to the
target dependencies in order to force their updates. This makes "make"
use libsepol.a in the linking command without using LDLIBS.
While at it, copy what commit 14d7064348 ("libselinux: Allow
overriding libsepol.a location during build") introduced in libselinux
Makefile by using a new LIBSEPOLA variable in all Makefiles.
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>