libcap: improved to check if we can build the pam module

base/libcap/libcap.conf

@@ -26,3 +26,10 @@ hook_add postdoc 5 "rm -rvf $root$docdir/old; cp -v `match_source_file -p capfaq
 #    make RAISE_SETFCAP=no install
 #
 var_append makeinstopt " " "RAISE_SETFCAP=no"
+
+# check if we can build the pam module which can be used to enforce inheritable
+# capability sets for a specified user
+if ! pkginstalled -f pam; then
+	var_append makeopt ' ' "PAM_CAP=no"
+	var_append makeinstopt ' ' "PAM_CAP=no"
+fi