Support Mac compilation under GitHub Actions

.github/workflows/ci.yml

@@ -3,7 +3,7 @@ name: ci
 on:
   push:
     branches:
-      - macos-ci
+      - macos-brew-motif
 
   pull_request:
     branches:
@@ -18,3 +18,16 @@ jobs:
       run: grep 'sudo apt install' INSTALL | sed 's/\$//' | sh
     - name: Compile
       run: make -C GUI/xephem
+
+  compile-macos:
+    runs-on: macos-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Install OpenMotif
+      run: brew install openmotif && brew info openmotif
+    - name: Install OpenSSL
+      run: brew install openssl && brew info openssl
+    - name: Install XQuartz
+      run: brew install xquartz --cask && brew info xquartz
+    - name: Compile
+      run: make -C GUI/xephem

GUI/xephem/Makefile

@@ -28,11 +28,20 @@ ifndef MOTIFL
 MOTIFL = /usr/lib
 endif
 
-# for linux and Apple OS X
+# For Linux and Apple OS X
+
+UNAME_S = $(shell uname -s)
+ifeq ($(UNAME_S),Darwin)
+  PLATI = -I/usr/local/opt/openssl@3/include
+#  -I/opt/X11/include
+  PLATL = -L/usr/local/opt/openssl@3/lib
+# -L/opt/X11/lib
+endif
+
 CC = gcc
 CLDFLAGS = -g
-CFLAGS = $(LIBINC) $(CLDFLAGS) -O2 -Wall -I$(MOTIFI) -I/opt/X11/include
-LDFLAGS = $(LIBLNK) $(CLDFLAGS) -L$(MOTIFL) -L/opt/X11/lib
+CFLAGS = $(LIBINC) $(CLDFLAGS) -O2 -Wall -I$(MOTIFI) $(PLATI)
+LDFLAGS = $(LIBLNK) $(CLDFLAGS) -L$(MOTIFL) $(PLATL)
 XLIBS = -lXm -lXt -lXext -lXmu -lX11
 LIBS = $(XLIBS) $(LIBLIB) -lm -lssl