encoding/json: faster encoding (CL 9129044).
net: improve windows performance by up to 30% (CL 8670044).
+Breaking change:
+archive/tar,archive/zip: fix os.FileInfo implementation to provide base name only (CL 13118043).
+
cmd/5a: removed support for R9/R10 (use m/g instead) (CL 9840043).
cmd/5l: add MOVBS, MOVHS etc for sub-word moves (CL 12682043).
cmd/cgo, cmd/go: support including C++ code with cgo (CL 8248043).