cmake: Define ENABLE_HEVC globally if set

CMakeLists.txt

@@ -33,6 +33,9 @@ endif()
 
 # Global project options
 option(ENABLE_HEVC "Enable HEVC encoders" OFF)
+if(ENABLE_HEVC)
+  add_compile_definitions(ENABLE_HEVC)
+endif()
 option(BUILD_FOR_DISTRIBUTION "Build for distribution (enables optimisations)"
        OFF)
 option(ENABLE_UI "Enable building with UI (requires Qt)" ON)