[llgo] irgen: expose DisableUnusedImportCheck flag

[axw]

LGTM

[axw]

This comment was removed by axw.

llgo/trunk/irgen/compiler.go

type CompilerOptions struct {
   // compiler will set this field automatically using MakeImporter().
   // If Importer is non-nil, InitMap must be non-nil also.
   InitMap map[*types.Package]gccgoimporter.InitData
 
   // PackageCreated is a hook passed to the go/loader package via
   // loader.Config, see the documentation for that package for more
   // information.
   PackageCreated func(*types.Package)
+
+  // DisableUnusedImportCheck disables the unused import check performed
+  // by go/types if set to true.
+  DisableUnusedImportCheck bool
 }
 
 type Compiler struct {
   opts       CompilerOptions
   dataLayout string
   pnacl      bool
 }
 
if compiler.Importer == nil {
     }
   }
 
   impcfg := &loader.Config{
     Fset: fset,
     TypeChecker: types.Config{
       Import: compiler.Importer,
       Sizes:  compiler.llvmtypes,
+      DisableUnusedImportCheck: compiler.DisableUnusedImportCheck,
     },
     Build:          &buildctx.Context,
     PackageCreated: compiler.PackageCreated,
   }
   // If no import path is specified, then set the import
   // path to be the same as the package's name.
   if importpath == "" {
     importpath = astFiles[0].Name.String()