With better directory layout and more proper include
statements we can avoid several local modifications,
such as changing config.h for Windows Glog and the
ones related on pass-through statements in logging
headers in Glog.
This commit also makes unused functions not-a-warning
for external code.
I've been using this fix in another branch locally, so it seems to work fine.
The other #ifdef checks should be checked on too, as __MINGW32__ and __MINGW64__
do NOT seem to be defined when compiling that file
