Define away some gcc garbage so that /usr/include/unistd.h will compile with...

Define away some gcc garbage so that /usr/include/unistd.h will compile with the CodeWarrior MachO target


git-svn-id: https://svn.apache.org/repos/asf/xerces/c/trunk@175707 13f79535-47bb-0310-9956-ffa450edef68