Document missing options: --with-efence and --with-bsm-audit

INSTALL

@@ -140,6 +140,13 @@ Special features/options:
 	`-l' will be prepended to it.  Multiple libraries may be
 	specified as long as they are space separated.
 
+  --with-efence
+	Link with the "electric fence" debugging malloc.
+
+  --with-bsm-audit
+	Enable support for sudo BSM audit logs on systems that support
+	it.  Currently only supported under FreeBSD and Mac OS X.
+
   --with-csops
 	Add CSOps standard options.  You probably aren't interested in this.