C++/Go/Java: Don't import top-level extensible predicates.

Author: aschackmull

cpp/ql/lib/semmle/code/cpp/dataflow/ExternalFlow.qll

@@ -101,7 +101,7 @@ private import internal.FlowSummaryImpl
 private import internal.FlowSummaryImpl::Public
 private import internal.FlowSummaryImpl::Private
 private import internal.FlowSummaryImpl::Private::External
-private import internal.ExternalFlowExtensions
+private import internal.ExternalFlowExtensions::Extensions as Extensions
 private import codeql.mad.ModelValidation as SharedModelVal
 private import codeql.util.Unit
 private import codeql.mad.static.MaD as SharedMaD

go/ql/lib/semmle/go/dataflow/ExternalFlow.qll

@@ -86,7 +86,7 @@
  */
 
 private import go
-private import internal.ExternalFlowExtensions
+private import internal.ExternalFlowExtensions::Extensions as Extensions
 private import FlowSummary as FlowSummary
 private import internal.DataFlowPrivate
 private import internal.FlowSummaryImpl

java/ql/lib/semmle/code/java/dataflow/ExternalFlow.qll

@@ -98,7 +98,7 @@ private import internal.FlowSummaryImpl
 private import internal.FlowSummaryImpl::Public
 private import internal.FlowSummaryImpl::Private
 private import internal.FlowSummaryImpl::Private::External
-private import internal.ExternalFlowExtensions
+private import internal.ExternalFlowExtensions::Extensions as Extensions
 private import codeql.mad.ModelValidation as SharedModelVal
 private import codeql.mad.static.MaD as SharedMaD