Report lli remote IO errors consistently

This enables IO error reports in both the child and server processes.

The scheme still isn't entirely satisfactory and output is jumbled but it beats
having no output at all. This will hopefully unblock ARM support (PR18057).

llvm-svn: 200017
diff --git a/llvm/tools/lli/RPCChannel.h b/llvm/tools/lli/RPCChannel.h
index d04c8c2..2d8c708 100644
--- a/llvm/tools/lli/RPCChannel.h
+++ b/llvm/tools/lli/RPCChannel.h
@@ -27,8 +27,6 @@
   RPCChannel() {}
   ~RPCChannel();
 
-  static void ReportError(int rc, size_t Size, std::string &ErrorMsg);
-
   /// Start the remote process.
   ///
   /// @returns True on success. On failure, ErrorMsg is updated with
@@ -40,8 +38,8 @@
   // This will get filled in as a point to an OS-specific structure.
   void *ConnectionData;
 
-  int WriteBytes(const void *Data, size_t Size);
-  int ReadBytes(void *Data, size_t Size);
+  bool WriteBytes(const void *Data, size_t Size);
+  bool ReadBytes(void *Data, size_t Size);
 
   void Wait();
 };