[compiler-rt] integer-truncation-blacklist.c: XFAIL on android/ios

The Builder sanitizer-x86_64-linux-android is failing
starting with rL338287 / D48959.

It runs the tests via android_compile.py, so i'm not sure this
is actually *this* issue:
  https://code.google.com/p/address-sanitizer/issues/detail?id=316
but this seems oddly similar to the other XFAIL'ed cases...

Right now that seems to be the only failing builder,
so i *think* it makes sense to try to just blacklist it for now.

llvm-svn: 338296