On linux, i have errors in xcb_conn.c and xcb_out.c, because 'caddr_t' is not declared. After some checks in the standard headers, i've found that it is defined only if __USE_BSD is defined (see sys/types.h) btw, why not using just a char * ?
I believe this bug is caused by having an old version of xproto installed that sets -D_XOPEN_SOURCE=500. I think I'm building in the same configuration you are but with up-to-date dependencies, and it works fine. I used caddr_t because that's how struct iovec is declared on Solaris and I'd had some difficulty with that in the past. Some general portability testing would be a good thing anyway.
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