[unittests] Enable debug info when compiling unittests when debug info is enabled.

I noticed this while I was debugging a failure in unittest.

Author: gottesmm

cmake/modules/AddSwiftUnittests.cmake

@@ -111,6 +111,12 @@ function(add_swift_unittest test_dirname)
     endif()
   endif()
 
+  is_build_type_with_debuginfo("${CMAKE_BUILD_TYPE}" HAS_DEBUG_INFO)
+  if (HAS_DEBUG_INFO)
+    set_property(TARGET "${test_dirname}" APPEND_STRING PROPERTY COMPILE_FLAGS
+      " -g ")
+  endif()
+
   file(RELATIVE_PATH relative_lib_path "${CMAKE_CURRENT_BINARY_DIR}" "${SWIFT_LIBRARY_OUTPUT_INTDIR}")
 
   if(SWIFT_HOST_VARIANT_SDK IN_LIST SWIFT_DARWIN_PLATFORMS)