Allow SIMD types in generics. Closes #10604
xfail a test to unblock the snapshot

cc #12021
auto merge of #12022 : alexcrichton/rust/unblock-snapshot, r=thestinger

cc #12021
extra: Move uuid to libuuid
cc #8784
auto merge of #11912 : poiru/rust/8784-libuuid, r=alexcrichton

cc #8784
Simd feature gating + Win32/64 fixes.
Added missing xfail-fast.
auto merge of #11717 : DiamondLovesYou/rust/master, r=alexcrichton

Note that it still doesn't allow generic types to be marked with #[simd].
move concurrent stuff from libextra to libsync