Add hybrid assembler concept to ARM assembler.

src/IceGlobalContext.h

Index: src/IceGlobalContext.h
diff --git a/src/IceGlobalContext.h b/src/IceGlobalContext.h
index baab9ca6b3ec78a9b1f610d8162458d1cbcc2a77..e4b14409c0d48475b343cbef1e3b8afc636560f6 100644
--- a/src/IceGlobalContext.h
+++ b/src/IceGlobalContext.h
@@ -175,6 +175,7 @@ public:
   Ostream &getStrDump() { return *StrDump; }
   Ostream &getStrError() { return *StrError; }
   Ostream &getStrEmit() { return *StrEmit; }
+  void setStrEmit(Ostream &NewStrEmit) { StrEmit = &NewStrEmit; }
 
   LockedPtr<ErrorCode> getErrorStatus() {
     return LockedPtr<ErrorCode>(&ErrorStatus, &ErrorStatusLock);