Amazon Linux 2023: find the resource dir when using the default triple

...instead of the vendor one.

This matches the behaviour of clang and clang18 that ships as part of
the distribution.

Resolves swiftlang/swift#84363

Author: edymtt

clang/lib/Driver/ToolChains/Gnu.cpp

@@ -2331,7 +2331,8 @@ void Generic_GCC::GCCInstallationDetector::AddDefaultGCCPrefixes(
   // lists should shrink over time. Please don't add more elements to *Triples.
   static const char *const AArch64LibDirs[] = {"/lib64", "/lib"};
   static const char *const AArch64Triples[] = {
-      "aarch64-none-linux-gnu", "aarch64-redhat-linux", "aarch64-suse-linux"};
+      "aarch64-none-linux-gnu", "aarch64-redhat-linux", "aarch64-suse-linux",
+      "aarch64-amazon-linux"};
   static const char *const AArch64beLibDirs[] = {"/lib"};
   static const char *const AArch64beTriples[] = {"aarch64_be-none-linux-gnu"};