reflect: implement method values

Fixes issue 1517.

R=golang-dev, r
CC=golang-dev
https://codereview.appspot.com/7906043
debug/elf: restore Go 1.0 semantics for (*File).Symbols

Also adjust the implementation of applyRelocationsAMD64
so that the test added in CL 6848044 still passes.

R=golang-dev, minux.ma
CC=golang-dev
https://codereview.appspot.com/7686049