drone: round two, and remove broken Windows image.

The Windows image lacks the required tooling.

.drone.yml

@@ -1,10 +1,26 @@
 kind: pipeline
-name: default
+name: gcc/amd64/linux
+
+platform:
+  arch: amd64
+
+steps:
+- name: build
+  image: gcc
+  pull: true
+  commands:
+  - ./tools/ci-build.sh
+
+---
+kind: pipeline
+name: gcc/arm64/linux
+
+platform:
+  arch: arm64
 
 steps:
-- name: mingw32
-  image: teaci/msys32
-  shell: mingw32
+- name: build
+  image: gcc
   pull: true
   commands:
   - ./tools/ci-build.sh

README.md

@@ -2,8 +2,8 @@
 
 | Environment | Status |
 | -------- | ------ |
-| Travis (Linux / Mac OS X) | [![Build Status](https://travis-ci.org/concurrencykit/ck.svg)](https://travis-ci.org/concurrencykit/ck)
-| Drone (Windows) | [![Build Status](https://cloud.drone.io/api/badges/concurrencykit/ck/status.svg)](https://cloud.drone.io/concurrencykit/ck)
+| Drone | [![Build Status](https://cloud.drone.io/api/badges/concurrencykit/ck/status.svg)](https://cloud.drone.io/concurrencykit/ck)
+| Travis | [![Build Status](https://travis-ci.org/concurrencykit/ck.svg)](https://travis-ci.org/concurrencykit/ck)
 
 ### Build