MacOSX 10.10: Resolve "UNKNOWN attrlist flags 0:0x10000000.  Fixes
#340722.  Patch from Rhys Kidd (rhyskidd@gmail.com)



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14708 a5019735-40e9-0310-863c-91ae7b9d1cf9