[lldb] Add import-std-module/sysroot to the libc++ test category.

We essentially test libc++ in a sysroot here so let's make sure
that we actually only run this test on platforms where libc++
testing is enabled.

llvm-svn: 374572

lldb/packages/Python/lldbsuite/test/commands/expression/import-std-module/sysroot/TestStdModuleSysroot.py

@@ -11,6 +11,10 @@ class ImportStdModule(TestBase):
 
     mydir = TestBase.compute_mydir(__file__)
 
+    # We only emulate a fake libc++ in this test and don't use the real libc++,
+    # but we still add the libc++ category so that this test is only run in
+    # test configurations where libc++ is actually supposed to be tested.
+    @add_test_categories(["libc++"])
     @skipIf(compiler=no_match("clang"))
     def test(self):
         self.build()