containsInterfaces -> definesInterfaces

There are two functions in HIDL, containsInterfaces
and containsInterface. The first checks if a Scope
defines interfaces. The second checks if a CompoundType
has an interface in its definition. This is confusing
so, I'm renaming the former to something more
appropriate.

Bug: 111320612
Test: N/A
Change-Id: I5939fee61c8f7b41cc9ef4fd7eb35dd669eff432
diff --git a/AST.cpp b/AST.cpp
index 81f8c0b..de69965 100644
--- a/AST.cpp
+++ b/AST.cpp
@@ -83,8 +83,8 @@
     return mRootScope.getInterface() != nullptr;
 }
 
-bool AST::containsInterfaces() const {
-    return mRootScope.containsInterfaces();
+bool AST::definesInterfaces() const {
+    return mRootScope.definesInterfaces();
 }
 
 status_t AST::postParse() {