Squashed commit of the following:

minor code cleanups:

commit ef41ff8f99ec8de50032ded6873de226d3f47dc4
Author: Alec Salazar <alec.j.salazar@gmail.com>
Date:   Tue Aug 5 09:10:54 2014 -0400

    replace __va_list with va_list

    most of the codebase already uses va_list, which is specified by
    iso-c. gcc/glibc provides 'typedef __gnuc_va_list va_list'. and
    when not using gcc/glibc we can't expect to find __gnuc_va_list.

commit 5d00656706d160dbf096849c2d0d7d268339858e
Author: Alec Salazar <alec.j.salazar@gmail.com>
Date:   Sun Aug 10 21:23:13 2014 -0400

    fix incorrect include redirects

    changes include headers sys/errno to errno
    sys/signal to signal and wait to sys/wait

commit 44f60a038eac0e933eb6e6b37d9b121a4e085874
Author: Alec Salazar <alec.j.salazar@gmail.com>
Date:   Tue Aug 5 10:53:16 2014 -0400

    undefine pagesize

    add undef PAGESIZE to clear redefinition warning on platforms
    where this value is already set, maintaining current behavior of
    retrieving this value from POSIX defined sysconf(_SC_PAGESIZE).