trinity: undefined UIO_MAXIOV need sys/io.h

trinity: undefined UIO_MAXIOV need sys/io.h

This upstream patch fixes the build error produced by building for
powerpc 32bit after the glibc bump to 2.26 with the following internal
toolchain config.

gcc5.4.0
glibc2.26
bin2.28.1
linux4.1.43

Failure log:
  CC	net/proto-ipv4.o
net/proto-ipv4.c: In function ‘ip_setsockopt’:
net/proto-ipv4.c:231:49: error: ‘UIO_MAXIOV’ undeclared (first use in this function); did you mean ‘_IO_MAGIC’?
   so->optlen = rnd() % sizeof(unsigned long)*(2*UIO_MAXIOV+512);
                                                 ^~~~~~~~~~
                                                 _IO_MAGIC

Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
[Arnout: add Matthew's Sob to the patch]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>