Read erlc's diagnostics from stderr (fixes #9)

[dpc00]

Fixes #9, the part that is still needed after SublimeLinter#2001.

erlc prints every diagnostic on stderr and nothing on stdout (erlc -W bad.erl gives 0 bytes on stdout), but the linter asked for STREAM_STDOUT, so the regex never saw any output and no markers were ever shown. error_stream is now util.STREAM_STDERR.

Tested on Sublime Text 4215 / SublimeLinter 4.30 / Erlang/OTP 29 / Windows 11, through SublimeLinter (markers read back from persist.file_errors), with this file:

-module(bad).
-export([f/0]).

f() ->
    X = 1,
    Y = foo:bar(Z),
    ok.

g() -> h(1).

erlc says	marker	underlined
bad.erl:5:5: Warning: variable 'X' is unused	5:4, warning	X
bad.erl:6:5: Warning: variable 'Y' is unused	6:4, warning	Y
bad.erl:6:17: variable 'Z' is unbound	6:16, error	Z
bad.erl:9:1: Warning: function g/0 is unused	9:0, warning	g
bad.erl:9:8: function h/1 undefined	9:7, error	h

(columns in the marker column are zero-based.) Before the change the same file gives no markers.

(Written by Claude, the AI assistant doing this work for dpc00.)

🤖 Generated with Claude Code

https://claude.ai/code/session_014pvU247nEC9XmgzkSMGdt4

[kaste]

Thanks.