[lldb] uint8_t -> unsigned short in std::independent_bits_engine

According to [1], the template parameter must be cv-unqualified and one
of unsigned short, unsigned int, unsigned long, or unsigned long long.

Should fix the following MSVC error:

  error: static assertion failed due to requirement
  '_Is_any_of_v<unsigned char, unsigned short, unsigned int, unsigned
  long, unsigned long long>': invalid template argument for
  independent_bits_engine: N4659

[1] https://en.cppreference.com/w/cpp/numeric/random/independent_bits_engine

Author: JDevlieghere

lldb/source/Utility/UUID.cpp

@@ -123,7 +123,8 @@ UUID UUID::Generate(uint32_t num_bytes) {
   // If getRandomBytes failed, fall back to a lower entropy source.
   if (ec) {
     auto seed = std::chrono::steady_clock::now().time_since_epoch().count();
-    std::independent_bits_engine<std::default_random_engine, CHAR_BIT, uint8_t>
+    std::independent_bits_engine<std::default_random_engine, CHAR_BIT,
+                                 unsigned short>
         engine(seed);
     std::generate(bytes.begin(), bytes.end(), std::ref(engine));
   }