Subzero: Fix target attribute when SZTARGET is defined.

src/IceCompileServer.cpp

Index: src/IceCompileServer.cpp
diff --git a/src/IceCompileServer.cpp b/src/IceCompileServer.cpp
index 2f1d9103e124184b4b9e0c0eaab9593cc0c0bfc4..994eae24e86bc7c84427958e26a6eeb9a2143b16 100644
--- a/src/IceCompileServer.cpp
+++ b/src/IceCompileServer.cpp
@@ -156,7 +156,7 @@ struct {
 /// Dumps values of build attributes to Stream if Stream is non-null.
 void dumpBuildAttributes(Ostream &Str) {
 // List the supported targets.
-#define SUBZERO_TARGET(TARGET) Str << "target_" #TARGET << "\n";
+#define SUBZERO_TARGET(TARGET) Str << "target_" XSTRINGIFY(TARGET) "\n";
 #include "SZTargets.def"
   const char *Prefix[2] = {"no", "allow"};
   for (size_t i = 0; i < llvm::array_lengthof(ConditionalBuildAttributes);