[scudo] Update ring buffer test to make it accept zero size

[Chia-hungDuan]

Summary

allocation ring buffer is allowed to be zero. Update the logic in the
test so that on the platform that disables it won't fail this case.

compiler-rt/lib/scudo/standalone/tests/combined_test.cpp

for (int i = 1; i < 32; ++i) {
     for (int i = 0; i < nPtrs; ++i)
       Allocator->deallocate(Ptrs[i], Origin);
   }
 }
 
 SCUDO_TYPED_TEST(ScudoCombinedTest, RingBufferSize) {
   auto *Allocator = this->Allocator.get();
   auto Size = Allocator->getRingBufferSize();
-  ASSERT_GT(Size, 0u);
+  if (Size > 0)
     EXPECT_EQ(Allocator->getRingBufferAddress()[Size - 1], '\0');
 }
 
 SCUDO_TYPED_TEST(ScudoCombinedTest, RingBufferAddress) {
   auto *Allocator = this->Allocator.get();
   auto *Addr = Allocator->getRingBufferAddress();
   EXPECT_NE(Addr, nullptr);
   EXPECT_EQ(Addr, Allocator->getRingBufferAddress());
 }