Don't override user provided compile definitions (backport #145) (#147)

* Don't override user provided compile definitions (#145)

* Don't override user provided compile definitions

Signed-off-by: Emerson Knapp <emerson.b.knapp@gmail.com>
(cherry picked from commit 454a7bc)

rosidl_typesupport_cpp/cmake/rosidl_typesupport_cpp_generate_interfaces.cmake

@@ -95,8 +95,8 @@ set_target_properties(${rosidl_generate_interfaces_TARGET}${_target_suffix}
     CXX_STANDARD 14)
 
 if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  set_target_properties(${rosidl_generate_interfaces_TARGET}${_target_suffix}
-    PROPERTIES COMPILE_OPTIONS -Wall -Wextra -Wpedantic)
+  target_compile_options(${rosidl_generate_interfaces_TARGET}${_target_suffix}
+    PRIVATE -Wall -Wextra -Wpedantic)
 endif()
 
 # if only a single typesupport is used this package will directly reference it