UnixPkg: Allow build.sh/build64.sh to be run from the edk2 root

You can now use this sequence to build UnixPkg:
$ cd /path/to/edk2
$ UnixPkg/build.sh
   or
$ UnixPkg/build64.sh

The old method is still valid:
$ cd /path/to/edk2/UnixPkg
$ ./build.sh

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@10934 6f19259b-4bc3-4df7-8a09-765794883524
2 files changed