[lld] [lld][COFF] Add per-target runtime directories to library search path (PR #227744)

[Martin Storsjö via llvm-commits]

================
@@ -204,6 +204,23 @@ static bool compatibleMachineType(COFFLinkerContext &ctx, MachineTypes mt) {
   }
 }
 
+static std::optional<std::string>
+perTargetRuntimeDirForMachineType(MachineTypes mt) {
+  switch (mt) {
+  case ARM64:
+  case ARM64X:
+    return {"aarch64-pc-windows-msvc"};
+  case ARM64EC:
+    return {"arm64ec-pc-windows-msvc"};
+  case AMD64:
+    return {"x86_64-pc-windows-msvc"};
+  case I386:
+    return {"i686-pc-windows-msvc"};
+  default:
----------------
mstorsjo wrote:

Could you add an `ARM` case as well? Those triples are usually written as `armv7-...`.

https://github.com/llvm/llvm-project/pull/227744