[gn build] Port b8f0ca0

Author: llvmgnsyncbot

llvm/utils/gn/secondary/lldb/source/Utility/BUILD.gn

@@ -22,6 +22,7 @@ static_library("Utility") {
     "DataExtractor.cpp",
     "Diagnostics.cpp",
     "Environment.cpp",
+    "ErrorMessages.cpp",
     "Event.cpp",
     "FileSpec.cpp",
     "FileSpecList.cpp",