[gn build] Port b971d4d

Author: llvmgnsyncbot

llvm/utils/gn/secondary/bolt/lib/Target/AArch64/BUILD.gn

@@ -7,7 +7,10 @@ static_library("AArch64") {
     "//llvm/lib/Support",
     "//llvm/lib/Target/AArch64/MCTargetDesc",
   ]
-  sources = [ "AArch64MCPlusBuilder.cpp" ]
+  sources = [
+    "AArch64MCPlusBuilder.cpp",
+    "AArch64MCSymbolizer.cpp",
+  ]
 
   # This target reaches into the internal headers of LLVM's AArch64 library.
   # That target doesn't expect that, so it doesn't use public_deps for