Add call instructions to Subzero's bitcode reader.

src/IceInst.cpp

Index: src/IceInst.cpp
diff --git a/src/IceInst.cpp b/src/IceInst.cpp
index b84266aa1a0ca80aa2fc8e0aa27a4cd85d49f35a..d6e0f59b15d30d1ad4236f00cfe020765310819d 100644
--- a/src/IceInst.cpp
+++ b/src/IceInst.cpp
@@ -566,6 +566,12 @@ void InstBr::dump(const Cfg *Func) const {
   Str << "label %" << getTargetFalse()->getName();
 }
 
+Type InstCall::getReturnType() const {
+  if (Dest == NULL)
+    return IceType_void;
+  return Dest->getType();
+}
+
 void InstCall::dump(const Cfg *Func) const {
   Ostream &Str = Func->getContext()->getStrDump();
   if (getDest()) {