cc rust-lang#48468

- The bootstrap crate currently passes -v to Cargo if itself invoked
with -vv.  But Cargo supports -vv (to show build script output), so make
bootstrap pass that if itself invoked with -vvv.  (More specifically,
pass N '-v's to Cargo if invoked with N+1 of them.)

- bootstrap.py currently tries to pass on up to two '-v's to cargo when
building bootstrap, but incorrectly ('-v' is marked as 'store_true', so
argparse stores either False or True, ignoring multiple '-v's).  Fix
this, allow passing any number of '-v's, and make it consistent with
bootstrap's invocation of Cargo (i.e. subtract one from the number of
'-v's).

- Also improve bootstrap.py's config.toml 'parsing' to support arbitrary
verbosity levels, + allow command line to override it.

...due to unresolved macros.

Closes rust-lang#49044

Support extra-verbose builds

- The bootstrap crate currently passes -v to Cargo if itself invoked with -vv.  But Cargo supports -vv (to show build script output), so make bootstrap pass that if itself invoked with -vvv.  (More specifically, pass N '-v's to Cargo if invoked with N+1 of them.)

- bootstrap.py currently tries to pass on up to two '-v's to cargo when building bootstrap, but incorrectly ('-v' is marked as 'store_true', so argparse stores either False or True, ignoring multiple '-v's).  Fix this, allow passing any number of '-v's, and make it consistent with bootstrap's invocation of Cargo (i.e. subtract one from the number of '-v's).

- Also improve bootstrap.py's config.toml 'parsing' to support arbitrary verbosity levels, + allow command line to override it.

…elision, r=cramertj

resolve `'_` in `dyn Trait` just like ordinary elision

r? @cramertj

Fixes rust-lang#48468

add intrinsics for portable packed simd vector reductions

Adds the following portable vector reduction intrinsics:

* fn simd_reduce_add<T, U>(x: T) -> U;
* fn simd_reduce_mul<T, U>(x: T) -> U;
* fn simd_reduce_min<T, U>(x: T) -> U;
* fn simd_reduce_max<T, U>(x: T) -> U;
* fn simd_reduce_and<T, U>(x: T) -> U;
* fn simd_reduce_or<T, U>(x: T) -> U;
* fn simd_reduce_xor<T, U>(x: T) -> U;

I've also added:

* fn simd_reduce_all<T>(x: T) -> bool;
* fn simd_reduce_any<T>(x: T) -> bool;

These produce better code that what we are currently producing in `stdsimd`, but the code is still not optimal due to this LLVM bug:  https://bugs.llvm.org/show_bug.cgi?id=36702

r? @alexcrichton

…matsakis

rustbuild: Add more MinGW libraries to ship

Closes rust-lang#49044

Faster submodule updating

For the common case when there are no submodules which need updating, this takes 0.48 seconds instead of 47 seconds.

r? @alexcrichton

Checks for unknown attributes before aborting due to unresolved macros

Fixes rust-lang#49074

The ``attribute `...` is currently unknown to the compiler`` error was not shown if there are any unresolved macros, which might be caused by mistyped `macro_use`.

Remove deprecated unstable alloc::heap::EMPTY constant

…aelwoerister

Only generate miri backtraces if explicitly requested

fixes rust-lang#49072
fixes rust-lang#48888

r? @michaelwoerister