xattr support would only be needed for the ability to upgrade / import from previous versions; these days we use Postgres instead of a file-based store, so no need for extended attributes once everything is running a modern version (and all data has been upgraded / imported).
If you don't need to upgrade from an ancient version, you can probably just comment out the appropriate bits in support/build.sh:
Index: support/build.sh
===================================================================
--- support/build.sh (revision 11097)
+++ support/build.sh (working copy)
@@ -736,9 +736,9 @@
"${svn_uri_base}/PyKerberos/trunk";
fi;
- py_dependency -v 0.5 -r 1038 \
- "xattr" "xattr" "xattr" \
+# py_dependency -v 0.5 -r 1038 \
+# "xattr" "xattr" "xattr" \
if [ -n "${ORACLE_HOME:-}" ]; then
local cx="cx_Oracle-5.1";