Function bodies are not yet hooked up because the node structure is not
100% correct. This commit establishes that we can correctly write bodies
out and read them in again.

- export and import all exported inlined function bodies:
  (export GO_GCFLAGS="-newexport"; sh all.bash) working
- inlined functions are not yet hooked up (just dropped on the floor)
- improved tracing output and error messages
- make mkbuiltin.go work for both textual and binary export data
  so we can run tests with the new format

Change-Id: I70dc4de419df1b604389c3747041d6dba8730b0b
Reviewed-on: https://go-review.googlesource.com/16284Reviewed-by: Matthew Dempsky <mdempsky@google.com>