Static binary crashes at startup when the command ends in an option-like argument (bash -i) #1575

Describe the bug

The static release binary crashes at startup (SIGSEGV) when the command's last argument looks like a ttyd option that takes a value, for example bash -i.

calc_command_start() in src/server.c copies argv into a buffer of exactly argc pointers, with no NULL terminator, and runs getopt_long over the copy. The command's trailing -i is parsed as ttyd's -i <interface> with its value missing. musl's getopt then advances optind to argc + 1 and permutes the array up to index argc, writing one pointer past the end of the heap buffer. musl's allocator detects the corruption at free(argv_copy) and traps (hlt, reported as SIGSEGV with si_code=SI_KERNEL).

On a real argv, slot argc is the NULL terminator, so the same permutation is harmless there. glibc builds may not show the problem; I only tested the musl static release binary.

To Reproduce

With the x86_64 static release binary of 1.7.7:

$ ttyd -p 7699 -i lo bash -i         # Segmentation fault, exit 139
$ ttyd -p 7699 -i lo bash -l         # runs
$ ttyd -p 7699 -i lo bash --noprofile  # runs
$ ttyd -p 7699 -i lo -- bash -i      # runs (workaround)

Two core dumps from real launches show the out-of-bounds slot directly:

• ttyd -p 7682 -i 127.0.0.1 -W -o bash --noprofile -i (argc = 10): the copy has room for 10 pointers; slot 9 holds NULL and slot 10, one past the end, holds "bash".
• A 20-argument launch ending in bash --noprofile --rcfile <file> -i: slot 20 holds a pointer to <file>.

Expected behavior

ttyd starts and runs bash -i.

Environment:

• ttyd 1.7.7-40e79c7 (x86_64 static release binary, libwebsockets 4.3.3)
• Arch Linux, kernel 7.2.5

Additional context

The code is unchanged on main as of 2922cb8. PR with a fix: keep a NULL terminator in the copy (#1576).