[clang] [libclang][test] Fix narrowing when initializing CXUnsavedFile::Length (PR #228405)

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@@ -118,6 +118,9 @@ struct CXUnsavedFile {
 
   /**
    * The length of the unsaved contents of this buffer.
+   *
+   * Note that this is an \c unsigned \c long, which has a platform-dependent
+   * width. Do not assume it is a 64-bit integer.
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UebelAndre wrote:

Updated!

https://github.com/llvm/llvm-project/pull/228405