Don't trust user data, http.zig edition

Recently, I was playing around with http.zig for recreational programming purposes and was surprised to see a Zig panic when I sent a hand-crafted request: thread 2173676 panic: integer overflow /tmp/http.zig/src/request.zig:859:28: 0x10eed04 in prepareForBody (example_1) const missing = cl - read; ^ /tmp/http.zig …