Merge pull request #79 from aalexand/aalexand-dev-dri

Do not attempt to symbolize /dev/dri/* and [heap] files.

profile/profile.go

 // locations can't be symbolized in principle, at least now.
 func (m *Mapping) Unsymbolizable() bool {
 	name := filepath.Base(m.File)
-	return name == "[vdso]" || strings.HasPrefix(name, "linux-vdso")
+	return name == "[vdso]" || strings.HasPrefix(name, "linux-vdso") || name == "[heap]" || strings.HasPrefix(m.File, "/dev/dri/")
 }
 
 // Copy makes a fully independent copy of a profile.