pkg/prog: Improve support for external debug info

Adds a config file option to allow specifying a list of directories to
search in when looking for seperate external debug info files.

Fixes #1353

pkg/proc/proc_linux_test.go

@@ -0,0 +1,39 @@
+package proc_test
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+
+	"github.com/derekparker/delve/pkg/proc/native"
+	protest "github.com/derekparker/delve/pkg/proc/test"
+)
+
+func TestLoadingExternalDebugInfo(t *testing.T) {
+	fixture := protest.BuildFixture("locationsprog", 0)
+	defer os.Remove(fixture.Path)
+	stripAndCopyDebugInfo(fixture, t)
+	p, err := native.Launch(append([]string{fixture.Path}, ""), "", false, []string{filepath.Dir(fixture.Path)})
+	if err != nil {
+		t.Fatal(err)
+	}
+	p.Detach(true)
+}
+
+func stripAndCopyDebugInfo(f protest.Fixture, t *testing.T) {
+	name := filepath.Base(f.Path)
+	// Copy the debug information to an external file.
+	copyCmd := exec.Command("objcopy", "--only-keep-debug", name, name+".debug")
+	copyCmd.Dir = filepath.Dir(f.Path)
+	if err := copyCmd.Run(); err != nil {
+		t.Fatal(err)
+	}
+
+	// Strip the original binary of the debug information.
+	stripCmd := exec.Command("strip", "--strip-debug", "--strip-unneeded", name)
+	stripCmd.Dir = filepath.Dir(f.Path)
+	if err := stripCmd.Run(); err != nil {
+		t.Fatal(err)
+	}
+}