Added github linux build action

.github/workflows/linux-ci.yml

@@ -0,0 +1,24 @@
+name: C/C++ CI
+
+on:
+  push:
+    tags:
+      - v**
+  workflow_dispatch:
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Install GCC11, pCap, wxWidgets
+      run: sudo apt update && sudo apt install -y gcc-11 g++-11 libwxgtk3.0-gtk3-dev && sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-11 110 --slave /usr/bin/g++ g++ /usr/bin/g++-11
+    - name: Display versions of tools and libraries
+      continue-on-error: true
+      run: uname -a; wx-config --list; wx-config --cxxflags; wx-config --libs; g++ --version | grep g++
+    - name: make
+      run: make
+    - name: Check binary file
+      run: ls -alh build/wxMahjong; file build/wxMahjong

Makefile

@@ -9,10 +9,13 @@ OBJECTS := $(addprefix $(BDIR)/,$(patsubst %.cpp,%.o,$(wildcard *.cpp)))
 $(BDIR)/%.o: %.cpp
 	$(CXX) -c `wx-config --cxxflags` -o $@ $<
 
-all: $(PROGRAM)
+all: $(BDIR) $(PROGRAM)
 
 $(PROGRAM): $(OBJECTS)
 	$(CXX) -o $(BDIR)/$(PROGRAM) $(OBJECTS) `wx-config --libs`
 
+$(BDIR):
+	mkdir $@
+
 clean:
 	rm -f $(BDIR)/*.o $(PROGRAM)