Derive Clone for Command and StdioContainer
librustc: Don't emit call for intrinsics instead just trans at callsite.
librustc: Remove old codepaths for creating intrinsic functions.
librustc: Update to reflect changes to how intrinsics are codegened.
librustc: Translate input for transmute directly into dest.
libcore: Reexport a couple of widely-used low-level intrinsics to reduce
code bloat.

This didn't make a difference in any compile times that I saw, but it
fits what we're doing with `transmute` and seems prudent.
mk: Don't run rustc manually during distcheck

This is already checked by the install script, no need to check it twice.
Add range lint for float literals, fixing #10934
typeck: check casts from pointers to floats, closes #15445
Guide: strings