[cmake] update for coverage test

CMakeLists.txt

@@ -10,6 +10,16 @@ project(
     LANGUAGES NONE
 )
 
+
+# Add coverage flags if the build type is Coverage
+if(CMAKE_BUILD_TYPE STREQUAL "Coverage")
+    if(CMAKE_C_COMPILER_ID MATCHES "GNU|Clang")
+        add_compile_options(--coverage)
+        link_libraries(--coverage)
+    endif()
+endif()
+
+
 include(cmake/variables.cmake)
 
 # ---- Declare library ----