Go: improve accuracy of overlay annotations

go/ql/lib/semmle/go/Decls.qll

@@ -1,7 +1,7 @@
 /**
  * Provides classes for working with declarations.
  */
-overlay[local]
+overlay[local?]
 module;
 
 import go
@@ -137,6 +137,7 @@ class FuncDef extends @funcdef, StmtParent, ExprParent {
   /**
    * Gets a call to this function.
    */
+  overlay[global]
   DataFlow::CallNode getACall() { result.getACallee() = this }
 
   /** Holds if this function is variadic. */

go/ql/lib/semmle/go/Scopes.qll

@@ -1,7 +1,7 @@
 /**
  * Provides classes for working with scopes and declared objects.
  */
-overlay[local]
+overlay[local?]
 module;
 
 import go
@@ -418,6 +418,7 @@ class Function extends ValueEntity, @functionobject {
    * This includes calls that target this function indirectly, by calling an
    * interface method that this function implements.
    */
+  overlay[global]
   pragma[nomagic]
   DataFlow::CallNode getACall() { this = result.getACalleeIncludingExternals().asFunction() }
 

go/ql/lib/semmle/go/dataflow/internal/DataFlowNodes.qll

@@ -1,4 +1,4 @@
-overlay[local]
+overlay[local?]
 module;
 
 private import go
@@ -488,6 +488,7 @@ module Public {
      * For virtual calls, we look up possible targets in all types that implement the receiver
      * interface type.
      */
+    overlay[global]
     Callable getACalleeIncludingExternals() {
       result = this.getACalleeWithoutVirtualDispatch()
       or
@@ -504,6 +505,7 @@ module Public {
      * As `getACalleeIncludingExternals`, except excluding external functions (those for which
      * we lack a definition, such as standard library functions).
      */
+    overlay[global]
     pragma[nomagic]
     FuncDef getACallee() { result = this.getACalleeIncludingExternals().getFuncDef() }