go/analysis: add Pass.OtherFiles field

This field lists the names of non-Go files that are part of the
package under analysis.

Change-Id: Ic967dc18b98e018c691442f7378cb29db30a1454
Reviewed-on: https://go-review.googlesource.com/138136
Reviewed-by: Michael Matloob <matloob@golang.org>

go/analysis/analysis.go

@@ -90,6 +90,8 @@ func (a *Analyzer) String() string { return a.Name }
 // program, and has both input and an output components.
 //
 // As in a compiler, one pass may depend on the result computed by another.
+//
+// The Run function should not call any of the Pass functions concurrently.
 type Pass struct {
 	// -- inputs --
 
@@ -98,6 +100,7 @@ type Pass struct {
 	// syntax and type information
 	Fset       *token.FileSet // file position information
 	Files      []*ast.File    // the abstract syntax tree of each file
+	OtherFiles []string       // names of non-Go files of this package
 	Pkg        *types.Package // type information about the package
 	TypesInfo  *types.Info    // type information about the syntax trees
 

go/analysis/internal/checker/checker.go

@@ -497,6 +497,7 @@ func (act *action) execOnce() {
 		Analyzer:          act.a,
 		Fset:              act.pkg.Fset,
 		Files:             act.pkg.Syntax,
+		OtherFiles:        act.pkg.OtherFiles,
 		Pkg:               act.pkg.Types,
 		TypesInfo:         act.pkg.TypesInfo,
 		ResultOf:          inputs,