[llvm-exegesis] move Mode from Key to BenchmarResult.

Moves the Mode field out of the Key. The existing yaml benchmark results can be fixed with the following script:

```
readonly FILE=$1
readonly MODE=latency # Change to uops to fix a uops benchmark.
cat $FILE | \
  sed "/^\ \+mode:\ \+$MODE$/d" | \
  sed "/^cpu_name.*$/i mode:            $MODE"
```

Differential Revision: https://reviews.llvm.org/D47813

Authored by: Guillaume Chatelet

llvm-svn: 334079
diff --git a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
index 75b2a1d..0599c8e 100644
--- a/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
+++ b/llvm/tools/llvm-exegesis/lib/BenchmarkRunner.cpp
@@ -37,7 +37,7 @@
   InstructionBenchmark InstrBenchmark;
 
   InstrBenchmark.Key.OpcodeName = State.getInstrInfo().getName(Opcode);
-  InstrBenchmark.Key.Mode = getMode();
+  InstrBenchmark.Mode = getMode();
   InstrBenchmark.CpuName = State.getCpuName();
   InstrBenchmark.LLVMTriple = State.getTriple();
   InstrBenchmark.NumRepetitions = NumRepetitions;