Fix two faulty LLVM version checks

What we actually want to do here is use the StringRef version in
versions newer than 3.8, and the void one in 3.8 and older.

Checking "major-version >= 3 && minor-version >= 9" does not do
what we want. Consider what this will do for version 4.0, for
which minor-version is zero...


[ROCm/hip commit: 3a2fe40f78]

projects/hip/hipify-clang/src/Cuda2Hip.cpp

@@ -3109,10 +3109,10 @@ public:
         // to workaround the 'const' MacroArgs passed into this hook.
         const Token *start = Args->getUnexpArgument(i);
         size_t len = Args->getArgLength(start) + 1;
-#if (LLVM_VERSION_MAJOR >= 3) && (LLVM_VERSION_MINOR >= 9)
-        _pp->EnterTokenStream(ArrayRef<Token>(start, len), false);
-#else
+#if (LLVM_VERSION_MAJOR == 3) && (LLVM_VERSION_MINOR == 8)
         _pp->EnterTokenStream(start, len, false, false);
+#else
+        _pp->EnterTokenStream(ArrayRef<Token>(start, len), false);
 #endif
         do {
           toks.push_back(Token());
@@ -4207,11 +4207,15 @@ void copyFile(const std::string& src, const std::string& dst) {
 int main(int argc, const char **argv) {
   auto start = std::chrono::steady_clock::now();
   auto begin = start;
-#if (LLVM_VERSION_MAJOR >= 3) && (LLVM_VERSION_MINOR >= 9)
-  llvm::sys::PrintStackTraceOnErrorSignal(StringRef());
-#else
+
+  // The signature of PrintStackTraceOnErrorSignal changed in llvm 3.9. We don't support
+  // anything older than 3.8, so let's specifically detect the one old version we support.
+#if (LLVM_VERSION_MAJOR == 3) && (LLVM_VERSION_MINOR == 8)
   llvm::sys::PrintStackTraceOnErrorSignal();
+#else
+  llvm::sys::PrintStackTraceOnErrorSignal(StringRef());
 #endif
+
   CommonOptionsParser OptionsParser(argc, argv, ToolTemplateCategory, llvm::cl::OneOrMore);
   std::vector<std::string> fileSources = OptionsParser.getSourcePathList();
   std::string dst = OutputFilename;