src: export the ParseEncoding function on Windows

[ivan]

Makes the ParseEncoding symbol visible to addons on Windows. It was already visible on Unices.

I ran into this when writing an addon that used ParseEncoding; the VS2013 build failed with:

(Link target) ->
  blake2.obj : error LNK2001: unresolved external symbol "enum node::encoding __cdecl node::ParseEncoding(class v8::Isolate *,class v8::Handle<class v8::Value>,enum node::encoding)" (?ParseEncoding@node@@YA?AW4encoding@1@PEAVIsolate@v8@@V?$Handle@VValue@v8@@@4@W421@@Z) [L:\home\at\NodeProjects\node-blake2\build\blake2.vcxproj]
  L:\home\at\NodeProjects\node-blake2\build\Release\blake2.node : fatal error LNK1120: 1 unresolved externals [L:\home\at\NodeProjects\node-blake2\build\blake2.vcxproj]

    9 Warning(s)
    2 Error(s)

It built fine after adding the NODE_EXPORT.

Similar to an older fix nodejs/node-v0.x-archive#3811

[Fishrock123]

cc @indutny / @bnoordhuis

[indutny]

Please move v8::Isolate* and friends on a next line at 4 space indent. No need to cascade things ;)

[ivan]

Thanks, fixed

[indutny]

Generally, LGTM. Is there anything else that needs exporting?

[ivan]

Generally, LGTM. Is there anything else that needs exporting?

Not that I know about, in node.h at least.

[indutny]

Ok, @Fishrock123 could you please land this?

[indutny]

@ivan btw, thank you for fixing this! ;)

[Fishrock123]

@indutny Yep, will do.

[Fishrock123]

Thanks, landed in c43855c