Fix building with cmake older than 3.12

CMakeLists.txt

@@ -169,7 +169,8 @@ set(CMAKE_XCODE_ATTRIBUTE_ONLY_ACTIVE_ARCH NO)
 set(CMAKE_XCODE_ATTRIBUTE_ONLY_ACTIVE_ARCH[variant=Debug] YES)
 
 if(ENABLE_SINGLE_APP_BUILD)
-	add_compile_definitions(SINGLE_PROCESS_APP=1)
+	add_definitions(-DSINGLE_PROCESS_APP=1)
+	#add_compile_definitions(SINGLE_PROCESS_APP=1) # requires cmake 3.12
 endif()
 
 if(APPLE_IOS)
@@ -276,7 +277,8 @@ if(NOT WIN32 AND NOT APPLE_IOS)
 endif()
 
 if(ENABLE_LUA)
-	add_compile_definitions(SCRIPTING_ENABLED=1)
+	add_definitions(-DSCRIPTING_ENABLED=1)
+	#add_compile_definitions(SCRIPTING_ENABLED=1) # requires cmake 3.12
 endif()
 
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