[gn build] Port ef2a104

Author: llvmgnsyncbot

llvm/utils/gn/secondary/clang/lib/AST/BUILD.gn

@@ -77,6 +77,7 @@ static_library("AST") {
     "ByteCode/Interp.cpp",
     "ByteCode/InterpBlock.cpp",
     "ByteCode/InterpBuiltin.cpp",
+    "ByteCode/InterpBuiltinBitCast.cpp",
     "ByteCode/InterpFrame.cpp",
     "ByteCode/InterpShared.cpp",
     "ByteCode/InterpStack.cpp",