Now that https://github.com/DiamondLovesYou/rust/issues/5 is fixed, remove the SYSROOT requirement.
Now that https://github.com/DiamondLovesYou/rust/issues/5 is fixed, remove the
SYSROOT requirement.

DiamondLovesYou/rust-ppapi,DiamondLovesYou/rust-ppapi,DiamondLovesYou/rust-ppapi,DiamondLovesYou/rust-ppapi