mdbx-ci: add Android for github.

Related to https://github.com/erthink/libmdbx/issues/258.

.github/actions/spelling/expect.txt

@@ -1069,6 +1069,7 @@ naumov
 nbytes
 ncpfs
 NDEBUG
+ndk
 nelem
 nentries
 nessdb
@@ -1152,6 +1153,7 @@ nthreads
 ntifs
 ntpl
 ntstatus
+nttld
 nullkey
 nullptr
 numdbs

.github/workflows/android.yml

@@ -0,0 +1,41 @@
+name: Android
+
+on:
+  pull_request:
+  push:
+    branches-ignore:
+    - coverity_scan
+    paths-ignore:
+    - '.circleci/**'
+    - '.github/actions/spelling/**'
+    - 'docs/**'
+    - 'packages**'
+    - .cirrus.yml
+    - .clang-format
+    - .gitignore
+    - .travis.yml
+    - AUTHORS
+    - COPYRIGHT
+    - ChangeLog.md
+    - LICENSE
+    - README.md
+    - appveyor.yml
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: fetch tags
+      run: git fetch --unshallow --tags --prune --force
+    - uses: nttld/setup-ndk@v1
+      id: setup-ndk
+      with:
+        ndk-version: r21e
+        add-to-path: true
+    - name: configure
+      env:
+        ANDROID_NDK_HOME: ${{ steps.setup-ndk.outputs.ndk-path }}
+      run: cmake --version && cmake --toolchain "${{ steps.setup-ndk.outputs.ndk-path }}/build/cmake/android.toolchain.cmake"
+    - name: build
+      run: cmake --build .