XFAIL: cond17.test on Mac OS X

[Rudá Moura]

Today i ran make check on automake-1.10.1 sources i've compiled on my  
Mac OS X (10.5.5) and I've got a fail test:

=====================================
1 of 554 tests failed
(60 tests were not run)
Please report to bug-automake@gnu.org
=====================================
make[3]: *** [check-TESTS] Error 1
make[2]: *** [check-am] Error 2
make[1]: *** [check-recursive] Error 1
make: *** [test] Error 2
=> XFAIL: cond17.test.