expose expeditor SIGWINCH state via `ee_pending_winch` #397

Job	Run time
ci (tpb, ubuntu-22.04, --pb --threads --enable-libffi, test-some-fast)	29m 27s
ci (a6osx, macos-13)	13m 53s
ci (ta6osx, macos-13)	18m 0s
ci (arm64osx, macos-14)	8m 35s
ci (tarm64osx, macos-14)	10m 53s
ci (i3le, ubuntu-22.04)	12m 36s
ci (ti3le, ubuntu-22.04)	15m 45s
ci (a6le, ubuntu-22.04)	9m 2s
ci (ta6le, ubuntu-22.04, CFLAGS+=-std=gnu89)	12m 13s
ci (ta6le, ubuntu-22.04, reboot, -m=ta6le --force, re.boot SCHEME="chezscheme", test-some-fast)	8m 27s
ci (i3nt, windows-2022, vs)	11m 45s
ci (ti3nt, windows-2022, vs)	15m 1s
ci (a6nt, windows-2022, vs)	11m 48s
ci (ta6nt, windows-2022, vs)	14m 57s
ci (ta6nt, windows-2022, gcc, CFLAGS+=-std=gnu89)	12m 56s
ci (ta6le, ubuntu-22.04, test-more, more)	57m 35s
	4h 22m 53s

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