TableGen/CodeGenSchedule: Move some getAllDerivedDefinitions() calls out of inner loops

This cuts the runtime of the two slowest tblgen invocations in aarch64
in half for me...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273235 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed