proc,service: return build informations for each package

Adds an API call that returns a list of packages contained in the
program and the files that were used to build them, and also a best
guess at which filesystem directory contained the package when it was
built.

This can be used by IDEs to map file paths if the debugging environment
doesn't match the build environment exactly.

service/debugger/debugger.go

@@ -1337,6 +1337,35 @@ func (d *Debugger) GetVersion(out *api.GetVersionOut) error {
 	return nil
 }
 
+// ListPackagesBuildInfo returns the list of packages used by the program along with
+// the directory where each package was compiled and optionally the list of
+// files constituting the package.
+func (d *Debugger) ListPackagesBuildInfo(includeFiles bool) []api.PackageBuildInfo {
+	d.processMutex.Lock()
+	defer d.processMutex.Unlock()
+	pkgs := d.target.BinInfo().ListPackagesBuildInfo(includeFiles)
+	r := make([]api.PackageBuildInfo, 0, len(pkgs))
+	for _, pkg := range pkgs {
+		var files []string
+
+		if len(pkg.Files) > 0 {
+			files = make([]string, 0, len(pkg.Files))
+			for file := range pkg.Files {
+				files = append(files, file)
+			}
+		}
+
+		sort.Strings(files)
+
+		r = append(r, api.PackageBuildInfo{
+			ImportPath:    pkg.ImportPath,
+			DirectoryPath: pkg.DirectoryPath,
+			Files:         files,
+		})
+	}
+	return r
+}
+
 func go11DecodeErrorCheck(err error) error {
 	if _, isdecodeerr := err.(dwarf.DecodeError); !isdecodeerr {
 		return err