[clang] [clang-tools-extra] [libcxx] [clang][Modules] Remove unnecessary includes of `Module.h` (PR #93417)

[kadir çetinkaya via cfe-commits]

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@@ -42,7 +41,11 @@
 #include <memory>
 #include <vector>
 
-namespace clang::clangd {
+namespace clang {
+
+class Module;
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kadircet wrote:

this is not an "unnecessary" include, clangd requires a declaration of `clang::Module` in this file (even if incomplete) and we try not to have forward declarations.

what's the motivation behind this change exactly?

https://github.com/llvm/llvm-project/pull/93417