Update tests to match modern diagnostics, again

Another almost-year, another batch of diagnostic changes.

Author: beccadax

test/NameLookup/module_selector.swift

@@ -10,7 +10,7 @@
 // * Whether X::foo finds foos in X's re-exports
 // * Whether we handle access paths correctly
 // * Interaction with ClangImporter
-// * Cross-module overlays, when those happen
+// * Cross-import overlays
 //
 // It also might not cover all combinations of name lookup paths and inputs.
 
@@ -266,37 +266,37 @@ func builderUser4(@Swift::MyBuilder fn: () -> Void) {}
 
 func whitespace() {
   Swift::print
-  // expected-error@-1 {{expression resolves to an unused function}}
+  // expected-error@-1 {{function is unused}}
 
   Swift:: print
-  // expected-error@-1 {{expression resolves to an unused function}}
+  // expected-error@-1 {{function is unused}}
 
   Swift ::print
-  // expected-error@-1 {{expression resolves to an unused function}}
+  // expected-error@-1 {{function is unused}}
 
   Swift :: print
-  // expected-error@-1 {{expression resolves to an unused function}}
+  // expected-error@-1 {{function is unused}}
 
   Swift::
   print
-  // expected-error@-1 {{expression resolves to an unused function}}
+  // expected-error@-1 {{function is unused}}
 
   Swift
   ::print
-  // expected-error@-1 {{expression resolves to an unused function}}
+  // expected-error@-1 {{function is unused}}
 
   Swift ::
   print
-  // expected-error@-1 {{expression resolves to an unused function}}
+  // expected-error@-1 {{function is unused}}
 
   Swift
   :: print
-  // expected-error@-1 {{expression resolves to an unused function}}
+  // expected-error@-1 {{function is unused}}
 
   Swift
   ::
   print
-  // expected-error@-1 {{expression resolves to an unused function}}
+  // expected-error@-1 {{function is unused}}
 }
 
 // Error cases
@@ -472,5 +472,5 @@ func badModuleNames() {
   // expected-error@-1 {{cannot find type 'NonexistentModule::MyType' in scope}}
 
   let y: A.NonexistentModule::MyChildType = fatalError()
-  // expected-error@-1 {{'NonexistentModule::MyChildType' is not a member type of 'A'}}
+  // expected-error@-1 {{'NonexistentModule::MyChildType' is not a member type of struct 'ModuleSelectorTestingKit.A'}}
 }