pam_krb5: Fix manual page in MIT case

* Always install the manual page as pam_krb5(8) regardless of which
  version we're using.
* Regenerate it using pod2mdoc instead of pod2man so it doesn't claim
  to be part of “User Contributed Perl Documentation”.
* Put the correct section number in the header and footer.
* Don't cross-reference non-existent pam(7) manual page.

Reviewed by:	cperciva
Differential Revision:	https://reviews.freebsd.org/D53885

ObsoleteFiles.inc

@@ -51,6 +51,9 @@
 #   xargs -n1 | sort | uniq -d;
 # done
 
+# 20251121: Remove duplicate pam_krb5 manual page
+OLD_FILES+=share/man/man8/pam-krb5.8.gz
+
 # 20251112: Remove old MLINK to apmconf(8)
 OLD_FILES+=share/man/man8/apmconf.8.gz
 

lib/libpam/modules/pam_krb5/Makefile

@@ -30,6 +30,7 @@ SRCDIR= ${SRCTOP}/contrib/pam-krb5
 .PATH:	${SRCDIR}/module \
 	${SRCDIR}/portable \
 	${SRCDIR}/pam-util \
+	${SRCDIR}/docs \
 	${SRCDIR}
 
 PACKAGE=	kerberos
@@ -57,8 +58,8 @@ SRCS=	account.c \
 	support.c \
 	vector.c
 
-MANNODEV=	pam-krb5.8
+MANNODEV=	pam_krb5.8
-MANNODEVLINKS=	pam-krb5.8 pam_krb5.8
+MANSRC.pam_krb5.8=pam-krb5.8
 
 CFLAGS=	-I${SRCDIR} \
 	-I${.CURDIR} \
@@ -74,6 +75,13 @@ pam-util_options.c:	.PHONY
 
 module_options.c:	.PHONY
 	cp ${SRCDIR}/module/options.c module_options.c
+
+.ifdef VENDOR_IMPORT
+# Regenerate the manual page from the pod source after vendor import
+pam-krb5.8: pam_krb5.pod
+	sed -e 's/pam(7)/pam.conf(5)/' <${.ALLSRC} | \
+	    pod2mdoc -n pam_krb5 -s 8 >${.CURDIR}/${.TARGET}
+.endif
 .else
 PACKAGE=	kerberos