Use SequenceEqual in win32 GetFullPath (#10706)

* Use SequenceEqual in win32 GetFullPath

This should be slightly more efficient since it's vectorizable.

* fixup! Use SequenceEqual in win32 GetFullPath

src/Framework/NativeMethods.cs

@@ -1546,6 +1546,7 @@ private static unsafe int GetFullPathWin32(string target, int bufferLength, char
     /// <returns>True only if the contents of <paramref name="s"/> and the first <paramref name="len"/> characters in <paramref name="buffer"/> are identical.</returns>
     private static unsafe bool AreStringsEqual(char* buffer, int len, string s)
     {
+#if CLR2COMPATIBILITY
         if (len != s.Length)
         {
             return false;
@@ -1560,6 +1561,9 @@ private static unsafe bool AreStringsEqual(char* buffer, int len, string s)
         }
 
         return true;
+#else
+        return MemoryExtensions.SequenceEqual(new ReadOnlySpan<char>(buffer, len), s.AsSpan());
+#endif
     }
 
     internal static void VerifyThrowWin32Result(int result)