[llgo] llgoi: Fix importing source packages together with dependent binary packages.

[pcc]

Summary

Note that this means that llgoi does not support the case
where a package's pkgpath is different from its import path,
but I don't think this should actually happen with llgoi.

[axw]

LGTM

cmd/llgoi/llgoi.go

if err != nil {
     return err
   }
 
   origImporter := in.copts.Importer
   in.copts.Importer = func(pkgmap map[string]*types.Package, pkgpath string) (*types.Package, error) {
     if pkg, ok := in.inputPkgmap[pkgpath]; ok {
       return pkg, nil
     }
+    if pkg, ok := pkgmap[pkgpath]; ok && pkg.Complete() {
+      return pkg, nil
+    }
     return origImporter(pkgmap, pkgpath)
   }
   return nil
 }
 
 func (in *interp) init() error {
   in.scope = make(map[string]types.Object)
   in.pkgmap = make(map[string]*types.Package)

test/llgoi/Inputs/src/bar/answer.go

 package bar
 
+import "strconv"
+
 func Answer() int {
-  return 42
+  n, _ := strconv.Atoi("42")
+  return n
 }

test/llgoi/import-source.test

 // RUN: env GOPATH=%S/Inputs llgoi < %s | FileCheck %s
 
 // make sure user symbols do not conflict with imported source package
 Answer := 1
 
 import "foo"
 // CHECK: # bar
 // CHECK: # foo
 
+// Test that importing binary after source works.
+import "strconv"
+
 foo.Answer()
 // CHECK: #0 int = 42
 
+strconv.FormatBool(true)
+// CHECK: #0 string = true
+
 import "foo_cgo"
 // CHECK: foo_cgo: cannot load cgo package

test/llgoi/import-source2.test

+// RUN: env GOPATH=%S/Inputs llgoi < %s | FileCheck %s
+
+// Test that importing binary before source works.
+import "strconv"
+
+import "foo"
+// CHECK: # bar
+// CHECK: # foo
+
+foo.Answer()
+// CHECK: #0 int = 42
+
+strconv.FormatBool(true)
+// CHECK: #0 string = true