- Set -Isrc/windows for mingw
- Check existence of sigaction, pread, and pwrite
- Provide alternative implementation of pread and pwrite
- Eliminate symlink code for OS_WINDOWS
- Don't check /proc/self/fd if the OS isn't linux
- Don't use MSVC specific declarations in port.h for mingw



git-svn-id: https://google-glog.googlecode.com/svn/trunk@135 eb4d4688-79bd-11dd-afb4-1d65580434c0