[lldb] Skip unique_ptr import-std-module tests on Linux

This seems to fail on ubuntu 18.04.5 with Clang 9 due to:

Error output:
error: Couldn't lookup symbols:
  std::__1::default_delete<int>::operator()(int) const

lldb/test/API/commands/expression/import-std-module/unique_ptr-dbg-info-content/TestUniquePtrDbgInfoContent.py

@@ -13,6 +13,7 @@ class TestUniquePtrDbgInfoContent(TestBase):
 
     @add_test_categories(["libc++"])
     @skipIf(compiler=no_match("clang"))
+    @skipIfLinux # s.reset() causes link errors on ubuntu 18.04/Clang 9
     def test(self):
         self.build()
 

lldb/test/API/commands/expression/import-std-module/unique_ptr/TestUniquePtrFromStdModule.py

@@ -13,6 +13,7 @@ class TestUniquePtr(TestBase):
 
     @add_test_categories(["libc++"])
     @skipIf(compiler=no_match("clang"))
+    @skipIfLinux # s.reset() causes link errors on ubuntu 18.04/Clang 9
     def test(self):
         self.build()