[clang] [llvm] Triple: Forward declare Twine and remove include (PR #145685)

[Nikita Popov via cfe-commits]

================
@@ -349,7 +350,12 @@ class Triple {
   /// triple fields unknown.
   Triple() = default;
 
+  LLVM_ABI explicit Triple(std::string &&Str);
----------------
nikic wrote:

Why `std::string &&` and `const std::string &` rather than one `std::string` ctor?

https://github.com/llvm/llvm-project/pull/145685