Codechange: split building into a library and executable

src/os/macosx/CMakeLists.txt

@@ -4,9 +4,12 @@ add_files(
     font_osx.h
     macos.h
     macos.mm
-    osx_main.cpp
     osx_stdafx.h
     string_osx.cpp
     string_osx.h
     CONDITION APPLE
 )
+
+if(APPLE)
+    target_sources(openttd PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/osx_main.cpp)
+endif()

src/os/os2/CMakeLists.txt

@@ -1,5 +1,8 @@
 add_files(
     os2.cpp
-    os2_main.cpp
     CONDITION OPTION_OS2
 )
+
+if(OPTION_OS2)
+    target_sources(openttd PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/os2_main.cpp)
+endif()

src/os/unix/CMakeLists.txt

@@ -1,6 +1,5 @@
 add_files(
     crashlog_unix.cpp
-    unix_main.cpp
     CONDITION UNIX AND NOT APPLE AND NOT OPTION_OS2
 )
 
@@ -13,3 +12,7 @@ add_files(
     font_unix.cpp
     CONDITION Fontconfig_FOUND
 )
+
+if(UNIX AND NOT APPLE AND NOT OPTION_OS2)
+    target_sources(openttd PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/unix_main.cpp)
+endif()

src/os/windows/CMakeLists.txt

@@ -6,6 +6,9 @@ add_files(
     string_uniscribe.h
     win32.cpp
     win32.h
-    win32_main.cpp
     CONDITION WIN32
 )
+
+if(WIN32)
+    target_sources(openttd PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/win32_main.cpp)
+endif()