Handles failing driver tests of clang

Added support for incremental mode 8 and 28 ie. `frontend::EmitBC:` and `frontend::PrintPreprocessedInput:`
Added supporting clang tests to test in clang-repl mode

Reviewed By: v.g.vassilev

Differential Revision: https://reviews.llvm.org/D125946

clang/lib/Interpreter/IncrementalParser.cpp

@@ -69,8 +69,12 @@ public:
             LLVM_FALLTHROUGH;
           case frontend::EmitAssembly:
             LLVM_FALLTHROUGH;
+          case frontend::EmitBC:
+            LLVM_FALLTHROUGH;
           case frontend::EmitObj:
             LLVM_FALLTHROUGH;
+          case frontend::PrintPreprocessedInput:
+            LLVM_FALLTHROUGH;
           case frontend::EmitLLVMOnly:
             Act.reset(new EmitLLVMOnlyAction(&LLVMCtx));
             break;

clang/test/Interpreter/incremental-mode.cpp

@@ -0,0 +1,3 @@
+// RUN: clang-repl -Xcc -E
+// RUN: clang-repl -Xcc -emit-llvm 
+// expected-no-diagnostics