[lldb][swift][nfc] Move async register function into header

This will enable this function to be reused.

Author: felipepiovezan

lldb/source/Plugins/LanguageRuntime/Swift/SwiftLanguageRuntime.cpp

@@ -2522,20 +2522,7 @@ void SwiftLanguageRuntime::DidFinishExecutingUserExpression(
 
 bool SwiftLanguageRuntime::IsABIStable() { FORWARD(IsABIStable); }
 
-namespace {
-/// The target specific register numbers used for async unwinding.
-///
-/// For UnwindPlans, these use eh_frame / dwarf register numbering.
-struct AsyncUnwindRegisterNumbers {
-  uint32_t async_ctx_regnum;
-  uint32_t fp_regnum;
-  uint32_t pc_regnum;
-
-  RegisterKind GetRegisterKind() const { return lldb::eRegisterKindDWARF; }
-};
-} // namespace
-
-static std::optional<AsyncUnwindRegisterNumbers>
+std::optional<AsyncUnwindRegisterNumbers>
 GetAsyncUnwindRegisterNumbers(llvm::Triple::ArchType triple) {
   switch (triple) {
   case llvm::Triple::x86_64: {

lldb/source/Plugins/LanguageRuntime/Swift/SwiftLanguageRuntime.h

@@ -517,6 +517,21 @@ class SwiftLanguageRuntime : public LanguageRuntime {
                              unsigned num_indirections = 0);
 };
 
+/// The target specific register numbers used for async unwinding.
+///
+/// For UnwindPlans, these use eh_frame / dwarf register numbering.
+struct AsyncUnwindRegisterNumbers {
+  uint32_t async_ctx_regnum;
+  uint32_t fp_regnum;
+  uint32_t pc_regnum;
+
+  /// All register numbers in this struct are given in the eRegisterKindDWARF
+  /// domain.
+  lldb::RegisterKind GetRegisterKind() const { return lldb::eRegisterKindDWARF; }
+};
+
+std::optional<AsyncUnwindRegisterNumbers>
+GetAsyncUnwindRegisterNumbers(llvm::Triple::ArchType triple);
 } // namespace lldb_private
 
 #endif // liblldb_SwiftLanguageRuntime_h_