gn build: Merge r350580.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350600 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/gn/secondary/llvm/tools/dsymutil/BUILD.gn b/utils/gn/secondary/llvm/tools/dsymutil/BUILD.gn
index b28c074..721b4c4 100644
--- a/utils/gn/secondary/llvm/tools/dsymutil/BUILD.gn
+++ b/utils/gn/secondary/llvm/tools/dsymutil/BUILD.gn
@@ -19,6 +19,7 @@
     "MachODebugMapParser.cpp",
     "MachOUtils.cpp",
     "NonRelocatableStringpool.cpp",
+    "SymbolMap.cpp",
     "dsymutil.cpp",
   ]
   if (host_os == "mac") {