Fixes #877: Remove appveyor configuration and badge;

See #877: there's an attempt to switch to Azure Pipelines.

appveyor.yml

@@ -1,28 +0,0 @@
-environment:
-  matrix:
-  - TARGET: x86_64-pc-windows-gnu
-    BITS: 64
-    MSYS2: 1
-  - TARGET: x86_64-pc-windows-msvc
-    BITS: 64
-  - TARGET: i686-pc-windows-gnu
-    BITS: 32
-    MSYS2: 1
-  - TARGET: i686-pc-windows-msvc
-    BITS: 32
-install:
-  - curl -sSf -o rustup-init.exe https://win.rustup.rs/
-  - rustup-init.exe -y --default-host %TARGET%
-  - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
-  - if defined MSYS2 set PATH=C:\msys64\mingw%BITS%\bin;%PATH%
-  - rustc -V
-  - cargo -V
-build: false
-test_script:
-  # TODO: Remove --no-default-features here. wabt and disass currently
-  # don't build on appveyor due to cmake issues.
-  - cargo build --verbose --all --no-default-features
-  - cargo test --verbose --all --no-default-features
-branches:
-  only:
-    - master

cranelift/README.md

@@ -8,7 +8,6 @@ into executable machine code.
 
 [![Documentation Status](https://readthedocs.org/projects/cranelift/badge/?version=latest)](https://cranelift.readthedocs.io/en/latest/?badge=latest)
 [![Travis Status](https://travis-ci.org/CraneStation/cranelift.svg?branch=master)](https://travis-ci.org/CraneStation/cranelift)
-[![Appveyor Status](https://ci.appveyor.com/api/projects/status/oub7wrrb59utuv8x?svg=true)](https://ci.appveyor.com/project/CraneStation/cranelift)
 [![Gitter chat](https://badges.gitter.im/CraneStation/CraneStation.svg)](https://gitter.im/CraneStation/Lobby)
 ![Minimum rustc 1.35](https://img.shields.io/badge/rustc-1.35+-green.svg)