Github workflow: checkstyle

Use github workflow to run checkstyle
- use free (for OS projects) resources
- starts for every commit and branch
- work on forks, contributors may use it
  before creating PRs

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Melikov <mail@gmelikov.ru>
Closes #10705

.github/workflows/checkstyle.yaml

@@ -0,0 +1,27 @@
+name: checkstyle
+
+on:
+  push:
+  pull_request_target:
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        ref: ${{ github.event.pull_request.head.sha }}
+    - name: Install dependencies
+      run: |
+        sudo apt-get install --yes -qq build-essential autoconf libtool gawk alien fakeroot linux-headers-$(uname -r)
+        sudo apt-get install --yes -qq zlib1g-dev uuid-dev libattr1-dev libblkid-dev libselinux-dev libudev-dev libssl-dev python-dev python-setuptools python-cffi python3 python3-dev python3-setuptools python3-cffi
+        # packages for tests
+        sudo apt-get install --yes -qq parted lsscsi ksh attr acl nfs-kernel-server fio
+        sudo apt-get install --yes -qq mandoc flake8 # devscripts - enable then bashisms fixed
+    - name: Prepare
+      run: |
+        sh ./autogen.sh
+        ./configure
+    - name: Checkstyle
+      run: |
+        make checkstyle