Code review comment for lp:~epics-core/epics-base/devlib2mmio

We forgot to test on Windows:

cl -nologo -D__STDC__=0 -D_CRT_SECURE_NO_DEPRECATE -D_CRT_NONSTDC_NO_DEPRECATE -Ox -GL -Oy- -W3 -w44355 -MT -I. -I../O.Common -I. -I. -I.. -I../../../../include/compiler/msvc -I../../../../include/os/WIN32 -I../../../../include -c ../epicsMMIOTest.c epicsMMIOTest.c
c:\jenkins\win32-1\workspace\epics-base-3.15-win32\include\os\win32\epicsMMIODef.h(116) : fatal error C1083: Cannot open include file: 'arpa/inet.h': No such file or directory

What is arpa/inet.h for?