[llvm] Triple: Fix handling of macos with unexpected target arches (PR #75469)

[Chris B via llvm-commits]

================
@@ -833,8 +831,10 @@ static Triple::ObjectFormatType getDefaultFormat(const Triple &T) {
       return Triple::COFF;
     else if (T.isUEFI())
       return Triple::COFF;
-    return Triple::ELF;
 
+    if (T.isOSDarwin())
----------------
llvm-beanz wrote:

nit: should we combine this with the two if's above and make it a switch on the OS (Windows, UEFI and Darwin are all OS bits)?

https://github.com/llvm/llvm-project/pull/75469