Adding GCC and RVCT support. Since edk uses [nmake] section we add to add <BuildOpito...

Adding GCC and RVCT support. Since edk uses [nmake] section we add to add <BuildOpitons> to pass the correct flags to the shell. I had to make lots of changes to the Shell svn r33 to make it compile for GCC and to compile with RVCT. I will post a diff to the discusion list and see how we should handle the Shell source code changes.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9404 6f19259b-4bc3-4df7-8a09-765794883524