[MiSched|TableGen] : Tidy up and modernise. NFC.

Replacing with range-based loop and substituting 'using'.

Reviewed by: @MatzeB
Differential Revision: https://reviews.llvm.org/D37748



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313140 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed