util: moving internal helpers to internal module

[thefourtheye]

1. Moving _errnoException and _exceptionWithHostPort to
   internal/util module as they are internal helper functions. They
   should not be exposed as part of the util module.
2. Issuing a deprecation warning when those functions are used.

[evanlucas]

Wouldn't this break graceful-fs again?

[vkurchatkin]

It would. It's probably better to add a test for this to prevent accidental breakage

[vkurchatkin]

@cjihrig why semver-major?

[brendanashworth]

Since this is going into an internal module, it doesn't need the underscore name.

Also, can we name the function (exports.errnoException = function errnoException(..) {) so we don't have to deal with exports.errnoException() below?

[brendanashworth]

I'm going to relabel this as semver-minor as backwards compatibility is kept.

[Fishrock123]

Isn't this useful for making errors from libuv bindings in userland?

[ChALkeR]

There are other modules this might break. But it's probably their fault.
For example, karma-assert sets util._errnoException for some reason:

k/karma-assert-1.0.0.tgz/assert.js:815:util._errnoException = function(err, syscall, original) {

[thefourtheye]

Closing this as it breaks graceful-fs and userland functions might make errors from libuv bindings with _errnoException helper.

[ChALkeR]

@thefourtheye Perhaps it's time to reopen and revisit, as #6413 is going to be landed soon?

We would probably need a deprecation message on util._errnoException, though.

[ChALkeR]

@thefourtheye, #6413 landed, nothing is blocking this anymore. Do you wish to redo/reopen this PR?