This commit is a 4x squash commit consisting of 4x functions converted to use FileCheck instead of grep.

Messages:
Converted test case trivial_codegen_tailcall.ll to use FileCheck.
Converted test return_constant.ll to use FileCheck instead of grep.
Converted test reorder_load.ll to use FileCheck instead of grep.
Converted test intervening-inst.ll to use FileCheck instead of grep.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172171 91177308-0d34-0410-b5e6-96231b3b80d8