[gn build] Port 47721d4

Author: llvmgnsyncbot

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

@@ -35,6 +35,7 @@ static_library("Utility") {
     "Log.cpp",
     "NameMatches.cpp",
     "ProcessInfo.cpp",
+    "RealpathPrefixes.cpp",
     "RegisterValue.cpp",
     "RegularExpression.cpp",
     "Scalar.cpp",