Change Shl<T, T> for Int to Shl<uint, T>
sync: Fail with init semaphore count < 0

Semaphores are not currently designed to handle this case correctly, leading to
very strange behavior. Semaphores as written are intended to count *resources*
and it's not possible to have a negative number of resources.

This alters the behavior and documentation to note that the task will be failed
if the initial count is 0.

Closes #15758
Remove misleading code example from The Guide

The removed code caused confusion because it is not clear that the type of `y` is actually `()`
Clean up some trait impls in core::num.

This removes the special casing for `float`s where it was not necessary, as
`-0.0 == 0.0`.
Derive Hash for TrieMap and TrieSet
Implement PartialEq, Eq for TrieMap, TrieSet
Revert "Made 'make install' include libs for additional targets"

This reverts commit 87334fb05ff2a665419241d877c13d6c4770a3f4.

Conflicts:
	mk/install.mk
Remove ancient GC cfg flags
auto merge of #15899 : aochagavia/rust/guide, r=kballard

The removed code caused confusion because it is not clear that the type of `y` is actually `()`
TreeMap examples fixes

1. Removed obsolete comment regarding recursive/iteration implementations of tree_find_with/tree_find_mut_with
2. Replaced easy breakable find_with example with simpler one (which only removes redundant allocation during search)
auto merge of #15900 : tbu-/rust/pr_numcleanup, r=kballard

This removes the special casing for `float`s where it was not necessary, as
`-0.0 == 0.0`.
auto merge of #15910 : sfackler/rust/nogc, r=cmr
auto merge of #15749 : vhbit/rust/treemap-doc-fixes, r=alexcrichton

1. Removed obsolete comment regarding recursive/iteration implementations of tree_find_with/tree_find_mut_with
2. Replaced easy breakable find_with example with simpler one (which only removes redundant allocation during search)
auto merge of #15902 : nham/rust/hash_triemap, r=alexcrichton

cc #15294
configure: Add --enable-dist-host-only flag

This preserves the current behavior of `make dist` where we only
distribute bins for the host architecture. The bots need this.
mk: Have the various flavors of 'dist' install all targets by default

Closes #15711
auto merge of #15928 : brson/rust/dist, r=alexcrichton,alexcrichton

The first commit reverts a similar fix that only solves the `make install` case. This adds the `--enable-dist-host-only` flag to configure to preserve the old behavior, which the nightly bots rely on. The bots will need to be updated soon after this lands (or they will ~double in size).

Closes https://github.com/rust-lang/rust/issues/15711
Parser: Global single-segment paths should be represented as PatEnum

Fixed #15774.
collections: Move push/pop to MutableSeq

Implement for Vec, DList, RingBuf. Add MutableSeq to the prelude.

Since the collections traits are in the prelude most consumers of
these methods will continue to work without change.

[breaking-change]
collections: Deprecate push_back/pop_back