Don't allow splitting on an empty configuration

When aapt breaks out splits, it may remove the SDK constraint [if
it's lower than the min sdk]. If that is the only constraint, we
would create a resource split with no constraints. Don't allow
that situation. There must always be _some_ constraint.

Bug: 113115970
Test: atest CtsAppSecurityHostTestCases:SplitTests
Test: aapt2_tests
Change-Id: I424c875677c3be2a3ff5ddd39100b998bd650a4b
diff --git a/tools/aapt2/split/TableSplitter.h b/tools/aapt2/split/TableSplitter.h
index 6aec257..ed24bc39 100644
--- a/tools/aapt2/split/TableSplitter.h
+++ b/tools/aapt2/split/TableSplitter.h
@@ -30,6 +30,7 @@
 
 struct SplitConstraints {
   std::set<ConfigDescription> configs;
+  std::string name;
 };
 
 struct TableSplitterOptions {