Mips.abiflags is a new implicitly generated section that  will be present on all new modules. The section contains a versioned data structure which represents essentially information to allow a program loader to determine the requirements of the application. This patch implements mips.abiflags section and provides test cases for it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212519 91177308-0d34-0410-b5e6-96231b3b80d8