IVGCVSW-4721 Make build of timelineDecoder.so depend only on BUILD_TIMELINE_DECODER

Change-Id: I49446f9fa8327a51bfc934dbb2d969a8e7367156
Signed-off-by: Jim Flynn <jim.flynn@arm.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 20e8717..f744785 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1000,9 +1000,11 @@
     addDllCopyCommands(ArmnnConverter)
 endif()
 
-if(BUILD_GATORD_MOCK)
+if(BUILD_TIMELINE_DECODER)
     add_subdirectory(src/timelineDecoder)
+endif()
 
+if(BUILD_GATORD_MOCK)
     set(gatord_mock_sources)
     list(APPEND gatord_mock_sources
         tests/profiling/gatordmock/CommandFileParser.hpp