[gn build] Add build file for clang/lib/Basic and dependencies

Adds a build file for clang-tblgen and an action for running it, and uses that
to process all the .td files in include/clang/Basic.

Also adds an action to write include/clang/Config/config.h and
include/clang/Basic/Version.inc.

Differential Revision: https://reviews.llvm.org/D55847

llvm-svn: 349677
diff --git a/llvm/tools/llvm-demangle-fuzzer/llvm-demangle-fuzzer.cpp b/llvm/tools/llvm-demangle-fuzzer/llvm-demangle-fuzzer.cpp
index 07c290a..017e85a 100644
--- a/llvm/tools/llvm-demangle-fuzzer/llvm-demangle-fuzzer.cpp
+++ b/llvm/tools/llvm-demangle-fuzzer/llvm-demangle-fuzzer.cpp
@@ -14,11 +14,19 @@
 #include <string>
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
-  std::string NullTerminatedString((const char *)Data, Size);
-  int status = 0;
-  if (char *demangle = llvm::itaniumDemangle(NullTerminatedString.c_str(), nullptr,
-                                         nullptr, &status))
-    free(demangle);
+  if (Size == 0)
+    return 0;
+
+  bool UseItanium = Data[0] < 128;
+  std::string NullTerminatedString((const char *)Data + 1, Size - 1);
+
+  if (UseItanium) {
+    free(llvm::itaniumDemangle(NullTerminatedString.c_str(), nullptr, nullptr,
+                               nullptr));
+  } else {
+    free(llvm::microsoftDemangle(NullTerminatedString.c_str(), nullptr, nullptr,
+                                 nullptr));
+  }
 
   return 0;
 }