[llvm] AArch64: Use RuntimeLibcallsInfo in SMEAttributes (NFC) (PR #164968)

[Benjamin Maxwell via llvm-commits]

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@@ -12,6 +12,9 @@
 #include "llvm/IR/Function.h"
 
 namespace llvm {
+namespace RTLIB {
+struct RuntimeLibcallsInfo;
+}
 
 class AArch64TargetLowering;
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MacDue wrote:

Remove the `AArch64TargetLowering` forward decl

https://github.com/llvm/llvm-project/pull/164968