Update PACKAGERS.md to explicitly talk about stripping, quoting Dave …

…Cheney from Golang upstream (who is very, very adamant about not stripping Golang compiled binaries)

While there, remove the now-outdated section about `CGO_ENABLED=0`

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)

hack/PACKAGERS.md

@@ -56,15 +56,40 @@ NOTE: if you''re not able to package the exact version (to the exact commit) of
 please get in touch so we can remediate! Who knows what discrepancies can be caused by even the
 slightest deviation. We promise to do our best to make everybody happy.
 
-## Disabling CGO
+## Stripping Binaries
 
-Make sure to disable CGO on your system, and then recompile the standard library on the build
-machine:
+Please, please, please do not strip any compiled binaries. This is really important.
 
-```bash
-export CGO_ENABLED=0
-cd /tmp && echo 'package main' > t.go && go test -a -i -v
-```
+See the following quotes from Dave Cheney, which explain this position better
+from the upstream Golang perspective.
+
+### [go issue #5855, comment #3](https://code.google.com/p/go/issues/detail?id=5855#c3)
+
+> Super super important: Do not strip go binaries or archives. It isn't tested,
+> often breaks, and doesn't work.
+
+### [launchpad golang issue #1200255, comment #8](https://bugs.launchpad.net/ubuntu/+source/golang/+bug/1200255/comments/8)
+
+> To quote myself: "Please do not strip Go binaries, it is not supported, not
+> tested, is often broken, and doesn't do what you want"
+>
+> To unpack that a bit
+>
+> * not supported, as in, we don't support it, and recommend against it when
+>   asked
+> * not tested, we don't test stripped binaries as part of the build CI process
+> * is often broken, stripping a go binary will produce anywhere from no, to
+>   subtle, to outright execution failure, see above
+
+### [launchpad golang issue #1200255, comment #13](https://bugs.launchpad.net/ubuntu/+source/golang/+bug/1200255/comments/13)
+
+> To clarify my previous statements.
+>
+> * I do not disagree with the debian policy, it is there for a good reason
+> * Having said that, it stripping Go binaries doesn't work, and nobody is
+>   looking at making it work, so there is that.
+>
+> Thanks for patching the build formula.
 
 ## Building Docker