[gn build] Port ca9d2e9

Author: llvmgnsyncbot

llvm/utils/gn/secondary/llvm/lib/Target/Hexagon/BUILD.gn

@@ -67,6 +67,7 @@ static_library("LLVMHexagonCodeGen") {
     "HexagonISelLowering.cpp",
     "HexagonISelLoweringHVX.cpp",
     "HexagonInstrInfo.cpp",
+    "HexagonLoopAlign.cpp",
     "HexagonLoopIdiomRecognition.cpp",
     "HexagonMCInstLower.cpp",
     "HexagonMachineFunctionInfo.cpp",