Turn on random access for Syzygy files in Windows (#1840)

* This is the Windows version of
#1829

No functional change.

src/syzygy/tbprobe.cpp

@@ -224,8 +224,9 @@ class TBFile : public std::ifstream {
             exit(1);
         }
 #else
+        // Note FILE_FLAG_RANDOM_ACCESS is only a hint to Windows and as such may get ignored.
         HANDLE fd = CreateFile(fname.c_str(), GENERIC_READ, FILE_SHARE_READ, nullptr,
-                               OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
+                               OPEN_EXISTING, FILE_FLAG_RANDOM_ACCESS, nullptr);
 
         if (fd == INVALID_HANDLE_VALUE)
             return *baseAddress = nullptr, nullptr;