Add ability for MCInstPrinters to add comments for instructions.
Enhance the x86 backend to show the hex values of immediates in
comments when they are large.  For example:

        movl    $1072693248, 4(%esp)    ## imm = 0x3FF00000



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95728 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 0abd485..b63427a 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -48,7 +48,10 @@
     : MCStreamer(Context), OS(os), MAI(mai), InstPrinter(printer),
       Emitter(emitter), CommentStream(CommentToEmit),
       IsLittleEndian(isLittleEndian), IsVerboseAsm(isVerboseAsm),
-      ShowFixups(showFixups), ShowInst(showInst) {}
+      ShowFixups(showFixups), ShowInst(showInst) {
+    if (InstPrinter && IsVerboseAsm)
+      InstPrinter->setCommentStream(CommentStream);
+  }
   ~MCAsmStreamer() {}
 
   bool isLittleEndian() const { return IsLittleEndian; }