Fix llvm-extract's "writing bitcode to a terminal" warning, which wasn't
working. To support this, add an is_displayed() function to raw_ostream,
and generalize Process::StandardOutIsDisplayed and friends in order to
support it.

Also, call RemoveFileOnSignal before creating a file instead of after, so
that the file isn't left behind if the program is interrupted between when
the file is created and RemoveFileOnSignal is called.

While here, add a -S to llvm-extract and port it to IRReader so that it
supports assembly input.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81568 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/opt/opt.cpp b/tools/opt/opt.cpp
index e470066..fe0e036 100644
--- a/tools/opt/opt.cpp
+++ b/tools/opt/opt.cpp
@@ -362,6 +362,10 @@
     // FIXME: outs() is not binary!
     raw_ostream *Out = &outs();  // Default to printing to stdout...
     if (OutputFilename != "-") {
+      // Make sure that the Output file gets unlinked from the disk if we get a
+      // SIGINT
+      sys::RemoveFileOnSignal(sys::Path(OutputFilename));
+
       std::string ErrorInfo;
       Out = new raw_fd_ostream(OutputFilename.c_str(), ErrorInfo,
                                raw_fd_ostream::F_Binary);
@@ -370,10 +374,6 @@
         delete Out;
         return 1;
       }
-
-      // Make sure that the Output file gets unlinked from the disk if we get a
-      // SIGINT
-      sys::RemoveFileOnSignal(sys::Path(OutputFilename));
     }
 
     // If the output is set to be emitted to standard out, and standard out is a