Integrate the functionality from runscript_selinux.so

runscript used to dlopen() runscript_selinux.so. This adds equivalent
functionality directly in to runscript instead. It authenticates with
either PAM or shadow and optionally has a dep on audit.

X-Gentoo-Bug: 517450
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=517450

mk/os-Linux.mk

@@ -9,6 +9,19 @@ LIBDL=		-Wl,-Bdynamic -ldl
 
 ifeq (${MKSELINUX},yes)
 CPPFLAGS+= -DHAVE_SELINUX
-LIBSELINUX= -lselinux
+LIBSELINUX?= -lselinux
 LDADD += $(LIBSELINUX)
+
+ifneq (${MKPAM},pam)
+# if using selinux but not pam then we need crypt
+LIBCRYPT?= -lcrypt
+LDADD += $(LIBCRYPT)
+endif
+
+endif
+
+ifeq (${MKAUDIT},yes)
+LIBAUDIT?=	-laudit
+CPPFLAGS+=	-DHAVE_AUDIT
+LDADD+=		${LIBAUDIT}
 endif

mk/pam.mk

@@ -3,6 +3,12 @@ LIBPAM?=	-lpam
 CPPFLAGS+=	-DHAVE_PAM
 LDADD+=		${LIBPAM}
 
+ifeq (${MKSELINUX},yes)
+# with selinux, pam_misc is needed too
+LIBPAM_MISC?=	-lpam_misc
+LDADD+=		${LIBPAM_MISC}
+endif
+
 PAMDIR?=	/etc/pam.d
 PAMMODE?=	0644
 else ifneq (${MKPAM},)