Sync patches r14006, r14034 and r14035 from main trunk.
1. Base on the value type to get the value for default opcode.
2. Base on the type field to generate numeric opcode.
3. Base on the type field to generate oneof opcode.

git-svn-id: https://svn.code.sf.net/p/edk2/code/branches/UDK2010.SR1@14778 6f19259b-4bc3-4df7-8a09-765794883524