mdbx-ci: add MinGW build.

Resolves Related to https://github.com/erthink/libmdbx/issues/155

Change-Id: I4419c4e494139e644ff0ed755ce4560000099d82

.github/actions/spelling/expect.txt

@@ -877,6 +877,7 @@ maindb
 mainpage
 maj
 majflt
+Makefiles
 MAKEFLAGS
 makeindex
 MAKELANGID
@@ -1324,6 +1325,7 @@ PWIN
 PWOF
 pwrite
 pwritev
+pwsh
 py
 pymdownx
 pyw

.github/workflows/MinGW.yml

@@ -0,0 +1,47 @@
+name: MinGW
+
+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: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [windows-latest]
+    steps:
+    - uses: actions/checkout@v2
+    - name: fetch tags
+      run: git fetch --unshallow --tags --prune --force
+    - name: configure
+      run: cmake  -G "MinGW Makefiles" .
+    - name: build
+      run: cmake --build .
+#    - name: test
+#      shell: pwsh
+#      run: |
+#        & mdbx_test.exe --progress --console=no --pathname=test.db --dont-cleanup-after basic > test.log
+#        Get-Content test.log | Select-Object -last 42
+#        if ($LastExitCode -ne 0) {
+#            throw "Exec: $ErrorMessage"
+#        } else {
+#            & mdbx_chk.exe -nvv test.db | Tee-Object -file chk.log | Select-Object -last 42
+#        }