[lldb] Fix -Wsign-compare in TestSectionSize.cpp (NFC)

In file included from /data/workspace/llvm-project/lldb/unittests/ObjectFile/PECOFF/TestSectionSize.cpp:10:
/data/workspace/llvm-project/third-party/unittest/googletest/include/gtest/gtest.h:1620:28: error: comparison of integers of different signs: 'c
onst unsigned long' and 'const int' [-Werror,-Wsign-compare]
GTEST_IMPL_CMP_HELPER_(NE, !=);
~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~

Author: DamonFool

lldb/unittests/ObjectFile/PECOFF/TestSectionSize.cpp

@@ -69,10 +69,10 @@ symbols:         []
   DataExtractor section_data;
   ASSERT_NE(object_file->ReadSectionData(swiftast_section.get(),
                                          section_data),
-            0);
+            (size_t)0);
 
   // Check that the section data size is equal to VirtualSize (496)
   // without the zero padding, instead of SizeOfRawData (512).
-  EXPECT_EQ(section_data.GetByteSize(), 496);
+  EXPECT_EQ(section_data.GetByteSize(), (uint64_t)496);
 }