fix: Use SyscallConn for isTTY which is safe during file close

[mafredri]

We now use (*os.File).SyscallConn in isTTY check which is safe during file close.

Added a test that produces the error and the change fixes it.

=== RUN   TestEntry
=== PAUSE TestEntry
=== CONT  TestEntry
=== RUN   TestEntry/isTTY_during_file_close
=== PAUSE TestEntry/isTTY_during_file_close
=== CONT  TestEntry/isTTY_during_file_close
==================
WARNING: DATA RACE
Read at 0x00c000094430 by goroutine 9:
  os.(*File).Fd()
      /usr/local/go/src/os/file_unix.go:89 +0xa4
  cdr.dev/slog/internal/entryhuman.isTTY()
      /home/mafredri/src/coder/slog/internal/entryhuman/entry.go:185 +0x98
  cdr.dev/slog/internal/entryhuman.shouldColor()
      /home/mafredri/src/coder/slog/internal/entryhuman/entry.go:189 +0x36
  cdr.dev/slog/internal/entryhuman.c()
      /home/mafredri/src/coder/slog/internal/entryhuman/entry.go:40 +0xc5
  cdr.dev/slog/internal/entryhuman.Fmt()
      /home/mafredri/src/coder/slog/internal/entryhuman/entry.go:54 +0x84
  cdr.dev/slog/internal/entryhuman_test.TestEntry.func8.1()
      /home/mafredri/src/coder/slog/internal/entryhuman/entry_test.go:106 +0x150

Previous write at 0x00c000094430 by goroutine 10:
  internal/poll.(*FD).destroy()
      /usr/local/go/src/internal/poll/fd_unix.go:86 +0xcb
  internal/poll.(*FD).decref()
      /usr/local/go/src/internal/poll/fd_mutex.go:213 +0x3e
  internal/poll.(*FD).Close()
      /usr/local/go/src/internal/poll/fd_unix.go:107 +0x84
  os.(*file).close()
      /usr/local/go/src/os/file_unix.go:262 +0x124
  os.(*File).Close()
      /usr/local/go/src/os/file_posix.go:25 +0x4b
  cdr.dev/slog/internal/entryhuman_test.TestEntry.func8.2()
      /home/mafredri/src/coder/slog/internal/entryhuman/entry_test.go:115 +0x4c

Goroutine 9 (running) created at:
  cdr.dev/slog/internal/entryhuman_test.TestEntry.func8()
      /home/mafredri/src/coder/slog/internal/entryhuman/entry_test.go:105 +0x1c5
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1576 +0x216
  testing.(*T).Run.func1()
      /usr/local/go/src/testing/testing.go:1629 +0x47

Goroutine 10 (finished) created at:
  cdr.dev/slog/internal/entryhuman_test.TestEntry.func8()
      /home/mafredri/src/coder/slog/internal/entryhuman/entry_test.go:114 +0x295
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1576 +0x216
  testing.(*T).Run.func1()
      /usr/local/go/src/testing/testing.go:1629 +0x47
==================
    testing.go:1446: race detected during execution of test
--- FAIL: TestEntry (0.00s)
    --- FAIL: TestEntry/isTTY_during_file_close (0.00s)
FAIL
FAIL	cdr.dev/slog/internal/entryhuman	0.032s
FAIL

[nhooyr]

Fascinating didn't know this was a thing. Nice!

[coveralls]

Pull Request Test Coverage Report for Build dccb6b21208886bec0e1fc63d71d4ed0bb1df864-PR-167

• 14 of 16 (87.5%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.2%) to 96.986%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/entryhuman/entry.go	14	16	87.5%

Totals
Change from base Build fd83a3567145b5f6fb420d911620938d9214ede7:	-0.2%
Covered Lines:	740
Relevant Lines:	763

---

💛 - Coveralls