Change raw_fd_ostream to take flags as an optional bitmask 
instead of as two bools.  Use this to add a F_Append flag
which has the obvious behavior.

Other unrelated changes conflated into this patch:

1. REmove EH stuff from llvm-dis and llvm-as, the try blocks
   are dead.
2. Simplify the filename inference code in llvm-as/llvm-dis,
   because raw_fd_ostream does the right thing with '-'.
3. Switch machine verifier to use raw_ostream instead of ostream
   (Which is the thing that needed append in the first place).




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79807 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/llvm-mc/llvm-mc.cpp b/tools/llvm-mc/llvm-mc.cpp
index 4f5b8a0..af72fbc 100644
--- a/tools/llvm-mc/llvm-mc.cpp
+++ b/tools/llvm-mc/llvm-mc.cpp
@@ -174,16 +174,18 @@
 }
 
 static formatted_raw_ostream *GetOutputStream() {
-  if (OutputFilename == "" || OutputFilename == "-")
-    return &fouts();
+  if (OutputFilename == "")
+    OutputFilename = "-";
 
   // Make sure that the Out file gets unlinked from the disk if we get a
-  // SIGINT
-  sys::RemoveFileOnSignal(sys::Path(OutputFilename));
+  // SIGINT.
+  if (OutputFilename != "-")
+    sys::RemoveFileOnSignal(sys::Path(OutputFilename));
 
   std::string Err;
-  raw_fd_ostream *Out = new raw_fd_ostream(OutputFilename.c_str(),
-                                           /*Binary=*/false, Force, Err);
+  raw_fd_ostream *Out = new raw_fd_ostream(OutputFilename.c_str(), Err,
+                                           raw_fd_ostream::F_Binary |
+                                         (Force ? raw_fd_ostream::F_Force : 0));
   if (!Err.empty()) {
     errs() << Err << '\n';
     if (!Force)