internal/gcimporter: avoid test assumptions about internal packages in other repos

TestImportedTypes was assuming that go/internal/gcimporter declares a
FindPkg function with a particular signature. However, since
go/internal/gcimporter is internal, it is not subject to Go 1
compatibility and its API is subject to change.

I intend to change it in CL 507360.

For golang/go#61064.

Change-Id: I994f5b967ce9c57d07ce1fe8b6ce900176848efa
Reviewed-on: https://go-review.googlesource.com/c/tools/+/511758
Auto-Submit: Bryan Mills <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
Run-TryBot: Bryan Mills <[email protected]>

Author: Bryan C. Mills

internal/gcimporter/gcimporter_test.go

@@ -395,7 +395,6 @@ var importedObjectTests = []struct {
 	{"math.Pi", "const Pi untyped float"},
 	{"math.Sin", "func Sin(x float64) float64"},
 	{"go/ast.NotNilFilter", "func NotNilFilter(_ string, v reflect.Value) bool"},
-	{"go/internal/gcimporter.FindPkg", "func FindPkg(path string, srcDir string) (filename string, id string)"},
 
 	// interfaces
 	{"context.Context", "type Context interface{Deadline() (deadline time.Time, ok bool); Done() <-chan struct{}; Err() error; Value(key any) any}"},