CMake: Add macro to wrap C++ command line definitions for swiftc

Similar to the existing macros for compile options and link options,
this macro wraps the command line definitions for swiftc in a way that
avoids warnings about conditional compilation flags not having values.

Meta/CMake/common_compile_options.cmake

@@ -14,6 +14,15 @@ macro(add_cxx_compile_options)
   add_compile_options($<$<COMPILE_LANGUAGE:C,CXX,ASM>:${args}>)
 endmacro()
 
+macro(add_cxx_compile_definitions)
+  set(args "")
+  foreach(arg ${ARGN})
+    string(APPEND args ${arg}$<SEMICOLON>)
+    add_compile_options("SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xcc -D${arg}>")
+  endforeach()
+  add_compile_definitions($<$<COMPILE_LANGUAGE:C,CXX,ASM>:${args}>)
+endmacro()
+
 macro(add_cxx_link_options)
   set(args "")
   foreach(arg ${ARGN})

Meta/CMake/fontconfig.cmake

@@ -3,5 +3,5 @@ include_guard()
 if (NOT APPLE AND NOT ANDROID)
     find_package(Fontconfig REQUIRED)
     set(HAS_FONTCONFIG ON CACHE BOOL "" FORCE)
-    add_compile_definitions(USE_FONTCONFIG=1)
+    add_cxx_compile_definitions(USE_FONTCONFIG=1)
 endif()

Meta/CMake/lagom_compile_options.cmake

@@ -18,7 +18,7 @@ if (NOT WIN32)
 endif()
 
 if (LINUX)
-    add_compile_definitions(_FILE_OFFSET_BITS=64)
+    add_cxx_compile_definitions(_FILE_OFFSET_BITS=64)
 endif()
 
 if (APPLE)

Meta/CMake/vulkan.cmake

@@ -5,6 +5,6 @@ if (NOT APPLE)
     find_package(Vulkan QUIET)
     if (VulkanHeaders_FOUND AND Vulkan_FOUND)
         set(HAS_VULKAN ON CACHE BOOL "" FORCE)
-        add_compile_definitions(USE_VULKAN=1)
+        add_cxx_compile_definitions(USE_VULKAN=1)
     endif()
 endif()