[RISCV] Extend test/CodeGen/RISCV/callee-saved-* to test getCalleePreservedRegs

Add a caller which exhausts regs then calls another function. This allows
getCalleePreservedRegs to be tested.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@356122 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed