cmd/compile, go/importer: minor cleanups

Change-Id: Ic7a1fb0dbbf108052c970a4a830269a5673df7df
Reviewed-on: https://go-review.googlesource.com/21963
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
diff --git a/src/cmd/compile/internal/gc/bexport.go b/src/cmd/compile/internal/gc/bexport.go
index e780bcf..59a85c2 100644
--- a/src/cmd/compile/internal/gc/bexport.go
+++ b/src/cmd/compile/internal/gc/bexport.go
@@ -59,9 +59,8 @@
 
 The export data starts with a single byte indicating the encoding format
 (compact, or with debugging information), followed by a version string
-(so we can evolve the encoding if need be), the name of the imported
-package, and a string containing platform-specific information for that
-package.
+(so we can evolve the encoding if need be), and then the package object
+for the exported package (with an empty path).
 
 After this header, two lists of objects and the list of inlined function
 bodies follows.