[lldb/test] Disable TestStringLiteralExpr.test on Windows

This test, introduced by b042d15d2e, fails on
https://lab.llvm.org/buildbot/#/builders/83/builds/20933/steps/7/logs/stdio

but succeeds on other targets, see for instance
https://lab.llvm.org/buildbot/#/builders/68/builds/35462/steps/6/logs/stdio

This test is not be arch specific, just disabling it on Windows.

lldb/test/Shell/Expr/TestStringLiteralExpr.test

@@ -1,3 +1,4 @@
+# UNSUPPORTED: system-windows
 # RUN: echo "int main() { return 0; }" | %clang_host -x c -o %t -
 # RUN: %lldb -s %s %t | FileCheck %s