[lldb][test] Disable vla test on Windows

For the same reasons as 6cfac49.

This test was added in llvm#100710.

It fails because when we're linking with link.exe, -gdwarf has no
effect and we get a PDB file anyway. The Windows on Arm lldb bot
uses link.exe.

 "C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\VC\\Tools\\MSVC\\14.34.31933\\bin\\Hostx86\\arm64\\link.exe" <...>

08/01/2024  01:47 PM         2,956,488 vla.cpp.ilk
08/01/2024  01:47 PM         6,582,272 vla.cpp.pdb
08/01/2024  01:47 PM           734,208 vla.cpp.tmp

(cherry picked from commit 229a165)

Author: DavidSpickett

lldb/test/Shell/SymbolFile/DWARF/vla.cpp

@@ -1,3 +1,6 @@
+// When linking with link.exe, -gdwarf still produces PDB instead.
+// UNSUPPORTED: system-windows
+
 // RUN: %clangxx_host -gdwarf -std=c++11 -o %t %s
 // RUN: %lldb %t \
 // RUN:   -o run \